This Teng Impact Socket has the following specification: Size: 17mm Length: 78mm The Teng Tools Deep Impact Sockets are specifically designed for use with power tools and air tools. They are manufactured from chrome molybdenum steel in accordance with GGG-W-6608, providing the highest quality. The sockets have a 1/2in drive, and are suitable for both industrial and automotive applications. Each socket is individually branded and size marked for quick identification.