we are a manufacturer of washers. 1)M10-M52 2)steel, ss304,316,etc. 3)ZP,HDG,black,etc. 4)din6916,din436,din440r,din127, STANDARD: SIZE: M3-M80,MATERIAL:MILD CARBON STEEL,SS304(A2),SS316(A4),HV140-HV200 CARBON STEELSURFACE TREATMENT:ZINC PLATED BLUE /WHITE,ZINC PLATED YELLOW,HOT DIPPED GALVANIZED,PLAIN,BLACK,PHOSPHATING.