plain flat washer for high strength bolts which standard is DIN6916 this plain flat washer is in high quality and zinc plated 1.material:carbon steel ,stainless steel2.standard:DIN,,ANSI,JIS,GB,ISO3.size:M12-M364.strength:high strength for bolts5.surface:plain,black,zinc plated,HDG6.packing:according to customers' requirement flat washer