Professional tool for commercial or occasional use. Manufactured from chrome vanadium steel for strength and durability. This is a 9mm Metric socket with a 1/4" drive, making it compatible with any 1/4" drive ratchets or bars. It is a shallow socket with a 6-sided / single hex design. The inside of the socket features a slot on the drive part, allowing ratchets with a ball bearing quick release function to lock into place, preventing the socket from falling off the ratchet during use. It also has a knurled ring for extra grip in oily or slippery conditions.