DIN 7971-C rounded head sheet metal screw with slot, ST4.2 x 9.5, Article number 7971C420091. Property class / material: ch, surface finish zinc plated. Rounded Head Sheet Metal Screw with Slot manufactured to DIN 7971-C with ISO 1478 tapping screw thread (ST) thread, coarse pitch, fully threaded. Standard parts to the same standard, property class, dimensions and surface finish are interchangeable between manufacturers; confirm the controlling standard revision, any class-society or application approval, and the mating thread before substitution.