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