Aco hexdrain. Designed with 8 possible outlet positions, this unique A15 channel drain can be used in domestic drainage projects such as along garage thresholds, landscaping projects and a range of DIY garden and patio applications. Aco hexdrain

 
 Designed with 8 possible outlet positions, this unique A15 channel drain can be used in domestic drainage projects such as along garage thresholds, landscaping projects and a range of DIY garden and patio applicationsAco hexdrain  The company offers various drainage systems specifically designed to manage stormwater runoff, protecting people from hazards and properties from potential damage

Features & Benefits: ACO Raindrain Domestic Channel Drain 1m x 118mm x 97mm - A15. ACO Hexdrain & ACO Raindrain "Complete The Look" Grating Galvanised Steel 1000mm A 15, part of the ACO range of elegant and modern grating finishes that provide choice and style to Complete the Look of driveways and patio projects. 00. Manufactured using recycled polypropylene; ACO HexDrain has a range of innovative features which makes installing drainage channels easier than ever. The corner unit is supplied with 4 x solid sides, any of these can be removed to allow rainwater to flow into or through the corner unit. ACO drains connect to your existing underground drainage, usually via an existing piece of above ground pipe connected to your. Collection Select your store. 80. Each channel comes complete with Heelguard black. Manufactured from recycled polypropylene, ACO HexDrain B 125 is suitable for vehicle traffic up to Load Class B 125 - Pedestrian precincts, light vehicles, private car parks and drives. Related CASE STUDIES Nov 2019. 5m. ACO India. Track and field drainage systems. It has a 4 way channel connection and a spigot for connection to 110mm diameter PVC-U pipesManufactured using 100% recycled polypropyleneSpecifically designed for slab and block pavingMakes installing domestic drainage easier than everCE marked and. ACO, Inc. It is able to accept inputs from any of the four sides, and also has a removable spigot to allow connection to a 110mm PVC-U pipe directly underneath. ACO Drain. For 300mm wide channels. 30kg per unit. Then go for the perfect finish. Add to basket. Manufactured from recycled polypropylene,ACO HexDrain?is suitable for a range ofdomestic applications, and its range ofinnovative features makes installing drainagechannels easier than ever. Dimensions: 125mm x 80mm x 1m. Unique shape helps to anchor the channel to the concrete surround. The corner of this unit is lightweight and easy to. ACO Hexdrain Plastic Channel Drainage Corner Unit and Vertical Outlet £24. PVC ACO Drainage channel Key features: 125mm x 80mm x 1 metre With plastic grating Easy to install Ideal for multiple locations. The new ACO RainDrain B 125 corner unit, features include: Cast iron grating. ACO’s driveway range meets the highest performance standards and are tested to withstand the rigours of everyday use. The HexDrain Brickslot Corner Unit can be installed at any location within a channel run, you may want to install just one as an outlet or multiple units for rainwater downpipes or as rodding eyes/access units. Manufactured from recycled polypropylene, ACO HexDrain is suitable for domestic applications up to Load Class A 15 - Pedestrian, cycleways, minimally trafficked areas (light domestic vehicles only). 99 incl VAT. Customer Reviews. The high quality, high strength channel system is available in lightweight 1 metre units, making ACO. 50. ACO Threshold Drain Drainage Channel with Stainless Steel Grating - 1m. ACO Threshold Drain comes complete with either a silver or black aluminium, CorTen steel or stainless steel Heelguard grating suitable for pedestrian traffic. Company Registration No: 01647362. 92" diameter outlet connects to ACO 8" Hygienic Floor Drain body. ACO HexDrain is a high-strength channel drain manufactured with a recycled polypropylene base for use in domestic applications. Hexdrain Brickslot is the perfect solution if you’re laying block paving or patio slabs. Price List. New ACO KerbDrain®: Recyclable, Sustainable. Each 1m length of ACO HexDrain® BrickSlot offers a cutting guide which makes it easy to cut an individual channel to length as well as a choice of eight vertical outlet positions for easy connection to a 110mm drainage pipe. Quantity. Sent from and sold by Build and Plumb Materials Online. . 03 £45. ACO Hexdrain No 19310 Channel + Black Plastic Grating 1000mm A15. The high quality ACO HexDrain Brickslot channels clip together, allowing for quick and easy installation. Quantity. ACO HexDrain is a drainage channel manufactured from recycled polypropylene, suitable for domestic applications up to Load Class A 15 - Pedestrian, cycleways, minimally trafficked areas (light domestic vehicles only). Fort Carson GSAB Maintenance Hangar. £11. To form a 90° angle you simply cut out the two relevant side sections and. ACO Drain consists of cast polymer concrete bodies with either galvanized steel, stainless steel or cast iron wearing edges. A drainage channel is usually a ground-level grate with a pipe underneath to carry the water away. Instead of having to look at a drain lid/grill there is just a strip visible along the top of the surface. 00 incl VAT. They include traditional antique cast iron and galvanised steel as well as more contemporary finishes such as. Installation device & template. 45. Channels are made from polymer concrete and are supplied complete with galvanized steel grates strong enough to withstand regular residential type car/4WD traffic. Delivery Free delivery available (restrictions apply) Log in to buy. Length 174mm x Diameter 118mm x Depth 250mm Weight 0. RainDrain B 125 is designed to be suitable for multiple applications, all of them domestic, for example: Patios, Paths, Courtyards, Thresholds and Perimeters, Pedestrian Areas and Garage Thresholds, Driveways* and Private Car Parks*. £18. Lightweight design. In this video, we look at how to clean and maintain an ACO drainage channel. Watch a video tutorial by ACO Technologies plc, a leading manufacturer of plastic drainage products. 00 incl VAT. This. Was: £17. Suitable for pedestrian/light vehicle traffic applications such as residential driveways, patios, basements, and pools. £48. £698. £15. ACO DrainMat is a high quality matwell assembly. . The end cap is used to seal the end of the drainage that prevents leakage. ACO Drain is available in 2″, 4”, 8” and 12” internal widths, and are available with up to 130 ft (40m) of built-in continuous slope. HexaLine is a recyclable polypropylene trench drain system with a range of innovative features, making installation easier than ever. Easy to install and fit together. Add to trolley. ACO HexDrain®/RainDrain® Gratings. The 1m channel is quick and easy to install and provides great drainage for excess water, for gardens, patios and driveways. The world’s most popular modular trench drain system. ACO HexDrain Corner Unit. ACO RainDrain B 125 Channel and Cast Iron Grating - 118mm x 97mm x 1000mm. Bottom outlet. Complete the system with ACO’s range of accessories, designed to aid simple and fast installationDrain rainwater reliably with the ACO Self modular system. ACO HexDrain + BrickSlot Accessory Bag. Easy to install with interlocking. £22. £21. ACO CivicDrain and StormBrixx specified for Oxfordshire barn conversion. ACO HexDrain® Brickslot channel assembly Product code Description Length (mm) Width Depth Invert Weight (kg) 319561 Channel with black platic slotted grating 1m 1000 125 148 143 1. VAT. 5 tonnes of weight. ACO Hexdrain 1mtr A15 Channel Drain Plastic with Grating . In this guide, we’re going to look at ACO drain installation. HexaLine Brickslot. All accessories are manufactured from recycled polypropylene (black plastic). Lightweight, cellular construction allows for a simple "push-fit" of channels and accessories. 4kg. Was: £17. The system prevents ponding and keep all surfaces clean and. ACO offer a range of “Complete the Look” gratings providing a choice of eight grating styles which can be fitted to our HexDrain channels to add the finishing touch to your project. VIEW PRODUCT. ACO's range of elegant and modern 'Complete the Look' gratings are available to provide choice and style. ACO HexDrain Brickslot is a discreet plastic slot drainage channel suitable for patio and garage threshold applications. ACO HexDrain Corner Unit - Plastic Grating - Vertical Outlet. Manufactured from Vienite, ACO's high strength polymer concrete material, ACO RainDrain is suitable for domestic applications up to Load Class A 15. Add to basket. Drainage channel grates have the advantage of draining along their entire length, so more significant volumes of water can be removed faster than with a single gully drain. ACO HexDrain is a high strength, high quality channel drainage system suitable for a range of domestic drainage applications. The HexDrain Brickslot channel should be installed 3-6mm lower than the surrounding surface finish. 10 x Black Ultra Low Profile Shallow Flow Drain Plastic Grating 50mm Deep x 1m Length x 125mm Width Drainage Channel. Channel Clips. Product Features. ACO Universal End Cap for HexDrain and RainDrain. Four knock out sides for connecting to channels. Complete the system with ACO’s range of accessories, designed to aid simple and fast installation This video will guide you through the typical process for installing ACO HexDrain channel drainage systems, which are perfectly suited for use in domestic ap. News. uk website: Heelguard™ gratings with 8mm slots. Manufactured from recycled polypropylene, ACO HexDrain Brickslot is suitable for pedestrian and vehicle traffic up to Load Class A 15. RainDrain B 125. Find out more about these organisations, and how we're working with their members below. drainage channel for domestic applications. Hexdrain 1m Channel with Galvanised Grating. Channels clip together for quick and simple on site fabrication. 41 Inc VAT £32. Manufactured using recycled polypropylene; ACO HexDrain has a range of innovative features which makes installing drainage channels easier than ever. ACO HexDrain® B 125 high quality, high strength light duty channel drainage system with Heelguard™ grating. ACO Raindrain Domestic Channel Drain 1m x 118mm x 97mm - A15. ACO connects and directs rainwater around the home ACO HexDrain is widely used around properties. Sign up today for a cash or credit account, exclusive discounts, rebates and rewards with a Building Superstore Account. HexaLine GaragePack ACO Self Installation Instructions Parts Table Accessory pack includes: 2 - closing end caps 1 - bottom outlet 1 - leaf guard Corner unit: Allows up to 4 way channel connection A full range of accessories are. RainDrain B 125. The robust system is certified for loads up to 250 tonnes per m2, making it ideal for: ACO GroundGuard is 90% porous, providing effective drainage of surface water and. 4kg. 99 £12. ACO Hexdrain Plastic Channel Drainage Corner Unit and Vertical Outlet £24. The HexDrain Sump Unit is designed to be installed in conjunction with either the corner unit or the outlet connector to provide a “catch pit” and a horizontal outlet connection onto 110mm diameter PVC-U underground. ACO HEXDRAIN SURFACE DRAINAGE CHANNEL BLACK DRIVEWAY CORNER, ACCESSORY, END CAP. ACO drains are a popular type of channel drain (sometimes called a linear drain), which drains surface water from paved, tarmacked or concrete surfaces, then redirects it to a main drainage system. Add to basket. ACO drainage system – Hexdrain Brickslot – Ideal for patios and block paving Hexdrain Brickslot is the perfect solution if you’re laying block paving or patio slabs. For a system that exudes the utmost quality, Anthracite grating is suitable for both traditional and contemporary settings, compliment your existing or new drainage with Anthracite. . ACO BIM Models Download for free. 00 Incl. 4. ACO Threshold Drains are ideal for use with block paving and are made from extruded plastic. ACO stands for professional drainage, efficient cleaning, and the controlled discharge or reuse of water. The ACO Drainlock grating has a bar-less locking device, allowing for quick and simple installation of gratings. 89. Park, Harry Weston Road, Coventry, CV3 2TT. This range of high quality gratings from ACO offers a broad range of options and finishes to suit any application and an easy upgrade to complement and enhance your landscaping materials and designs. You save: £14. The new range of elegant and modern 'Complete the Look. RainDrain Brickslot B 125. Unlike load-class A drainage products, these are safe to use on driveway entrances. ACO offer two downpipe connectors designed to be used in conjunction with the HexDrain corner unit. McAlpine Slimline Channel Drain With Brushed Finish Cover Plate 600mm. It is able to accept inputs from any of the four sides, and also has a removable spigot to allow connection to a 110mm PVC-U pipe directly underneath. ACO HexDrain B 125 comes complete with a corrosion resistant black composite Heelguard grating, ideal. Cutting Guides. To provide a watertight seal ACO. ADHX19280. The grating is designed to fit quickly and easily onto the HexDrain or RainDrain and gives it a rustic finish that is full of character. fit PVC-U 110mm pipework connection. Downloads. 📢 Introducing ACO KerbDrain® BridgeDeck With years of experience in designing and manufacturing combined kerb and #drainage systems, BridgeDeck has been engineered to provide the optimum water. Multiple catch basin options. Add to basket. ACO MultiDrain M100D - 135mm x 150mm x 1000mm. Add to basket. With ACO Complete the Look gratings you can choose between stainless steel, antique iron, plastic, and galvanized steel materials with a range of designs and finishes including a polished stainless steel or an anthracite grey coat. ACO helps give Markeaton Park new lease of life with green car park solution using ACO. The slotted gratings of the ACO Brickslot range enable particularly subtle drainage of your outdoor living areas. HexDrain Pro. ACO Water Management. Get a Selco Trade Card or login now. Rounded corners 1/8" or larger. Do you need a reliable and durable channel drain system for your landscape, pool or patio? Download the 2022 NDS Channel Drains Catalog and discover the wide range of products and solutions that NDS offers. Manufactured from recycled polypropylene, ACO HexDrain is suitable for domestic applications up to Load Class A 15 - Pedestrian, cycleways, minimally trafficked areas (light domestic vehicles only). ACO Hexdrain Channel Drain End Caps and Outlet Accessories Pack. The ACO Drainlock grating has a bar-less locking device, allowing for quick and simple installation of gratings. ACO Hygienic Cast Grate. 01 Ex VAT. Aco Hex Drain Garage Pack 3m. (2 grate styles available) 2 end caps. This ACO "Complete The Look" Antique Iron Heelguard Grating is manufactured from high quality cast iron and features an antique finish to make it both attractive and highly durable. High mechanical and chemical resistance. Popular amongst homeowners and property developers alike, the channel drain is simple to install and comes with nine other grating options so each system can be customised to the property it’s installed in front of. The high quality channels clip together al. You save: £6. Add to basket. But what happens when a new run of ACO HexDrain cuts across an existing downpipe and hopper gully. ACO MultiDrain M100D - 135mm x 150mm x 1000mm. Have more questions? Submit a request. These areas are often more exposed, receiving rainwater from the surface area plus other contributing areas, including run-down from the façade. Landscaping Associations. Not recommended for use in car parking areas. 88. Designed to be used with ACO’s best-selling domestic drainage channels ACO HexDrain and ACO RainDrain, a choice of styles ranging from contemporary stainless steel to antique cast iron options are available to provide the perfect finish. 64 inc VAT. The product range provides homeowners with a drainage solution that perfectly complements any style of patio project from slate to natural stone. Frameless design for optimum drainability and cleanibility. ACO Systems and Solutions Private Limited Third Floor, 627/4, 36B, II Phase, 60 Feet Road, Near NTTF, Chokkasandra, Peenya Bangalore - 560 058 Karnataka, IndiaACO HexDrain Pro comes complete with a corrosion resistant black composite Heelguard grating, ideal for pedestrian traffic. Marshalls Driveline Channel 200 x 200 x 65mm Charcoal Pack of 240. The discreet system has a width of 60mm and is available in 1m lengths. ACO HexDrain is a recycled polypropylene drainage channel that clips together and has an 80mm depth. The high quality ACO RainDrain channels interlock, allowing for quick and easy installation. Ideal for domestic and light vehicle traffic applications. Parts List. 39. ACO HexDrain Corner Unit - Plastic Grating - Vertical Outlet. £18. 35 ex. ACO hygienic cast grates with slip resistant finish. Features: Friction fit, anti-shunt grating eliminates movement; Easily cut to 500mm lengths; Heelguard™ grating suitable for pedestrian trafficProduct Description. Manufactured from recycled polypropylene, ACO HexDrain B125 is suitable for vehicle traffic up to Load Class B125 – Pedestrian precincts, light vehicles, private car parks and drives. ACO Hexdrain and Raindrain Wedge Wire Stainless Steel Grating - 1m £126. +. 80. Manufactured from recycled polypropylene, ACO HexDrain is suitable for domestic applications up to Load Class A 15 - Pedestrian, cycleways, minimally trafficked areas (light domestic vehicles only). 01 Ex VAT. The corner unit is lightweight and easy to handle and install. Designed to be easy to handle, the pack is wrapped in a waterproof cover and provides minimal packaging waste. ACO HexDrain Brickslot helps provide a step-free level threshold. £65. To find out more on Channel Drainage Maintenance, please visit our page: ACO HexDrain® B125 is a high quality, high strength light duty channel drainage system with a Heelguard™ grating. Features a knock-out for connection to a 110mm PVCu pipe. ACO hygienic drainage uses stainless steel floor drains to fulfil the strongest hygienic requirements to prevent bacterial contamination. 1-800-543-4764 info@acousa. Channel drainage is a key point in the management of surface water intercepting and conveying water to the next phase of it’s journey – a journey that has to be carefully and properly managed through cleaning, infiltration, attenuation and release. The ACO HexDrain system is made up of modular pre-formed channel units that are connected together to form a continuous drainage channel. . 3. Ideal for domestic applications and light duty applications. When installed with the HexDrain Brickslot corner unit (319560) the outlet spigot from the sump unit would have an invert depth of 345mm from finished ground level. ACO Technologies plc ACO Business Park, Hitchin Road, Shefford, Bedfordshire SG17 5TE Tel: 01462 816666 Fax: 01462 815895 e-mail: [email protected] website: PC21044ACO Hexdrain Plastic Channel Drainage Corner Unit and Vertical Outlet £24. On a terrace or balcony, the primary aim is to remove the water from the surface as soon as possible enabling safe access and preventing water ingress into a building. Channel weights are for fiberglass body only. <p>The ACO HexDrain Brickslot Corner Unit allows you to join up to 4 HexDrain Brickslot channels together. This product will allow you to join up to 4 Hexdrain Brickslot channels together and can&nbsp;accept inputs from any of its&nbsp;four sides. Different load class ratings can be achieved using different grate and channel combinations, as denoted below. Glue any fittings needed in the rainwater pipe. VAT. Manufactured from recycled polypropylene, ACO HexDrain is suitable for domestic applications up to Load Class A 15 - Pedestrian, cycleways, minimally trafficked areas (light domestic vehicles only). 50 incl VAT. ACO HexDrain B125 provides a drainage system for driveways and can be used for small private car park drainage. 00 incl VAT. ACO MultiDrain M100DS Sump with S/S Rails - 135mm x 635mm x 500mm £320. . ACO Drain systems consist of factory manufactured modular channel units made from corrosion resistant Polycrete channels, together with grates from a variety of materials for all loading applications. A fantastic, easy to install solution for domestic channel drainage. Shipping gipple/groove to ensure safer stacking for shipping and to minimize breakage. Maintenance solutions. ACO Drain systems are available in 50mm, 100mm, 200mm and 300mm internal widths, and are available with a built-in slope for up to 40 metres of. 00 incl VAT. What’s the HexDrain Sump Unit For? 4 years ago Updated. Drainage channel for domestic applications. £17. Hauraton Recyfix Pro 200 Service Channel with Ductile Iron Solid Cover - C250 £205. Manufactured from Vienite, ACO’s high strength polymer concrete material, ACO CivicDrain is suitable for vehicle traffic up to Load Class C 250. ACO Slimline is lightweight in design, and is approximately. The ACO corner unit allows you to join up to 4 HexDrain channels together. Channel systems including combined kerb drainage, grated or monocast are maintained in very much the same way as gullies and inter-connecting pipework, and use the same jetting equipment. HexDrain B 125 Closing endcap - 11085 . ACO at GaLaBau 2022. ACO: Delivery timescales are highlighted under the Add To Basket button, these are provided for UK Mailand deliveries only and are based on working days. Price List. VAT. VAT. An abutting edge rail for paviors of 10 cm height avoids unnecessary seams. This corner unit is manufactured from recycled polypropylene which ensures high strength. Shop online with Murdock Builders Merchants today. HHDCD00023. Add to basket. Add 2″ to length of each channel for female joining flange (only applicable at shallowest end of trench run). With all the features and benefits of our top selling ACO HexDrain channel, this is a convenient pack for a typical garage threshold installation. Add to Basket. ACO HexDrain is a plastic A15 load class channel drain built from recycled polypropylene for high strength and high durability. 89. Vertical outlet which is supplied with the accessory kit which is 110mm diameter. Add to basket. See us at. 45. Using our ‘Complete the look’ range, designed to be used with ACO’s best-selling domestic drainage channels ACO HexDrain® and ACO RainDrain®, you can pick from. Learn how to prepare and install ACO HexDrain drainage channels and accessories for patios, paths, pedestrian precincts and garage thresholds. In Stock. The ACO Drainlock grating has a bar-less locking device, allowing for quick and simple installation of gratings. 02 each. High quality polypropylene channel, suitable for pedestrian and vehicle traffic up to I . 69. ACO Utility Duct Modular polymer ducting system with lockable covers. ACO Hexdrain No 19310 Channel + Black Plastic Grating 1000mm A15. S300K. 5%) channel units – System numbering for proper installation. KS100 has a grade 304 stainless steel edge rail for use where increased aesthetics or corrosion resistance is required. Delivery. ACO HexDrain Accessory Bag. Check out HexaLine Brickslot for a more discreet, slot drainage solution for the HexaLine channel. . £7. Channel Drainage. Add to basket. If you find a product that achieves the required aesthetic but cannot find it on our website, please get in touch on 01666 577577 for more information or for a quote. Manufactured using recycled polypropylene, the high strength 1m channel comes. 50 incl VAT. 82 Inc VAT. Article is closed for comments. 30kg per unit. Click & Collect Available for collection. ACO HexDrain® Pro System Overview ACO HEXDRAIN PRO GRATING AND ACCESSORIES ACO Technologies plc ACO Business Park, Hitchin Road, Shefford, Bedfordshire SG17 5TE Tel: 01462 816666 Fax: 01462 815895 e-mail: technologies@aco. Length 174mm x Diameter 118mm x Depth 250mm Weight 0. accessory bag consists of: 2 x endcaps 1 x vertical outlet 110mm 1 x leaf guard 1 x instruction document Corner unit Sump unit Outlet connector Endcap Leaf guard ACO HexDrain. Sent from and sold by Trade Supplies Online. BOSS Soakaway Kit for Condesning Boilers. 85 Ex VAT £41. Designed to be easy to handle, the pack is wrapped in a waterproof cover and provides minimal packaging waste. ACO HexDrain is a plastic A15 load class channel drain built from recycled polypropylene for high strength and high durability. Please refer to our article “What’s. (319289). Easy to lift for quick maintenance and cleaning. Load Class B 125. Downpipe Connector 68mm Round (27120) Overall dimensions length 142mm x width 133mm x depth 48mm. Suitable for pedestrian/light vehicle traffic. Add to basket. Order Helpline ☎ 01752 692 221. 32. (319289). Suited to an assortment of domestic applications, the recycled polypropylene structure is ideal for pedestrian and light vehicular traffic up to Load Class A15. Suitable for use with RainDrain, HexDrain and. £58. Purchased Separately below. The high quality ACO HexDrain Brickslot channels clip together, allowing for quick and easy installation. AdLearn how to install HexDrain, a channel for draining water from the surface, on a concrete or asphalt bed. ACO India. ACO helps give Markeaton Park new lease of life with green car park solution using ACO GroundGuard. ACO Hexdrain. . ACO Channel Drain. 40 Incl. 24 in stock. The high quality, high strength channel system is available in lightweight 1 metre units, making ACO HexDrain quick and easy. Quick and easy to install. 49. All ACO BIM material is the property of ACO Technologies plc. Where Can HexDrain Be Installed?Features & Benefits: ACO Hexdrain Downpipe to Channel Drain Connector 68mm - Black. The B125 provides a drainage system for driveways and small private car parks. Complete the system with ACO’s range of accessories, designed to aid simple and fast installation. It is ideal for domestic patios, door threshold and light vehicle traffic applications such as. A15 load class for light vehicular traffic and pedestrian areas. The channels interlock allowing for quick and easy in. About ACO. Registered Office: Merchant House, Binley Business. Male and female connection to connect to ACO RainDrain channels. ACO Hexdrain C250 channel drains are a high quality channel drain manufactured from recycled polypropylene. 1" x 9. Part of the ACO range of elegant and modern grating finishes that provide choice and style to Complete the Look of driveways and patio projects. Galvanised steel grate withstands corrosion. Applications - - Garage thresholds - Patios and paths - Pedestrian precincts - Block pavingThe ACO HexDrain Brick slot Channel Black is a combination of the highly successful HexDrain with an offset slot cover, specifically designed to allow drainage points to be under block or slab paving up to 60mm deep, adjacent to wall thresholds. With a range of accessories available from corner units to ø110mm vertical outlets, it is now possible to use as. £17. ACO GM-X – galvanized steel pipe system (International)----Download: Building Materials: ACO access covers (International)----Download: Footer. The channels interlock allowing for quick and easy in. . The ACO Drainlock grating has a bar-less locking device, allowing for quick and simple installation of gratings.