Insert screwdriver bit set 1, material: S2 (hardness) 2, good quality 3, professional Insert screwdriver bit setManufacture and supply various full ... bits, nutsetters, nut drivers, sockets, socket adapters, bit holders and quick changeconnectors for screwdriver bitsmaterial types:Cr-V ... , Torx hollow, Torx plus, tri-wingType:single head, double head, head with round neck,non-magnetic and magnetic