Powerbuilt Impact Sockets and accessories feature an industrial grade Black Phosphate finish that prevents corrosion and extends the life of the tool. Each socket is made from impact-rated Chrome Molybdenum Steel material for added durability with laser-engraved size marking that won't rust or wear off - ever. Precision chamfered hex faces make it easier to guide onto fasteners and the exclusive Z-Drive 6 point hex pattern grabs and turns the flat surfaces of those fasteners to reduce round-off and slipping. Finally, socket center holes are punched through to add a bit more clearance for taller nuts and bolts. Powerbuilt impact socket and accessories offer the look, feel and performance hard-working Techs deserve and exceed ANSI standards for performance and quality. 7 Piece Impact Universal Joint & Socket Adapter Set