Professional tool for commercial or occasional use -Manufactured from chrome vanadium steel for strength and durability -5.5mm Metric socket -1/4" drive socket so will fit any 1/4" drive ratchets / bars -Shallow socket -6 sided / single hex socket -On the inside of the socket there is a slot on the drive part which allows ratchets with a ball bearing quick release function to lock into place so that the socket doesn’t fall off the ratchet whilst using this item. -Knurled ring for extra grip when using in oily slippy conditions