Powerbuilt Professional Technician socket sets are built to meet or exceed ANSI specifications. All sockets, socket accessories and drive tools are constructed of high-quality Chrome Vanadium (CR-V) steel with mirror polished chrome plated finish. Powerbuilt sockets are the heart of these sets. Their sleek chrome finish is enhanced with an easy to read size marking that is forged into the metal. Because it's forged into the socket wall, the marking won't rust or wear off - ever. Beauty is more than skin-deep though. Inside Powerbuilt sockets you'll find precision chamfered hex faces that make it easier to guide them onto fasteners. And the exclusive Z-Drive hex pattern grabs and turns the flat surfaces of those fasteners to reduce round-off and slipping. Finally, the center holes are punched through to add a bit more clearance for taller nuts and bolts. Each socket is mirror polished and chrome plated for the highest degree of durability and corrosion resistance. Powerful, precise and stylish, Powerbuilt socket sets offer the look, feel and performance hard-working Techs deserve.