General description Manufactured from hardened and tempered Chrome Vanadium steel, the Premier Lock-On Deep Impact Socket Set features a phosphate finish for added corrosion resistance. This 16-piece set includes specially machined flutes in the walls of the sockets, allowing for use on up to 85% rounded fasteners. The colour-coded rings facilitate fast identification, and the set is conveniently supplied in a storage case. SEALEY PREMIER offers a comprehensive range of hand tools suitable for daily professional use, and this set comes with a lifetime guarantee.