Description: Size : M2~M20 Length : 3mm~200mm Material : Carbon Steel / Stainless Steel Washer type : Round washer, Special washe, flat washer, external/internal lock washer, Split lock washer Surface Treatment : Zinc plated, Yellow Zinc plated, Black zinc, Zinc Nickel, Mechnical Galvanized, Ruspert, Slat Spray Test according to customer requirement. Standard : DIN, IFI, JIS, according to customer's drawing Package : Bulk packing, Box packing, Bag packing, Blister Sems screw Usage : Sems screw of high strength steel construction, it is used in railroad ,highway bridge, boiler steel construction, industry factory, building, tower, and crane. They require to use friction type of high strength sems screw. Sems screw's usage is connected to fasteners, and washer set on screw, as to it doesn't require washer during using. Sems screw has a special usage, that is anti-loose.