... screw / roof screw 1. Standards1. din75042. Material2. Stainless steel(SS304,SS316), carbon steel(C1022,1010,1008) copper, iron and so on. ... the loose at once8. Surface treatment8. Black oxide, zinc plated, chromium, and according your requirement9.Packing9. Bulk(25kgs/carton) ... price.3.material of our hex self drilling screw:stainless steel ,carbon steel,copper and so on4.surface treatment of this hex ...