Professional tool for commercial or occasional use. Manufactured from chrome vanadium steel for strength and durability. Heat treated and hardened with mirror polished finish. Supplied on spring tensioned clip rail. Never be stuck again in a tight unreachable place. Imperial / AF / SAE sizes. Useful for brake pipe / hydraulics lines etc... due to the fact that they grip almost all the way round where as spanners grip only on two sides, and the places where you use these sockets wont reach. Set Includes; sizes: 3/8" / 7/16" / 1/2" / 9/16" / 5/8" / 11/16" / 3/4" and 7/8" Comes complete on a 3/8" drive socket rail for easy storage and transportation.