... 40Mn2, 20MnSi Grade: 4.6, 5.6, 8.8 Surface:plain(oil),black,zinc,hdg double head screws in manufacturer in Foshan ... after-sale service5) free sample... Quick Details for double head screws in manufacturer in Foshan Type: ScrewsPlace of Origin: ... ,1/2"~4"Material: carbon steelHead CodeCSK, pan head, truss head, hexagon head, round head, oval head in cross recessed, combined, slotted, countersunk, flat, ...