Stanley Proto J72252 5 Piece 3/8" Drive Metric Hex Bit Socket Set Includes: 4mm, 5mm, 6mm, 8mm, 10mm, Socket Bar and Clips Proto 6 Point Impact Sockets are ideal for use on stubborn or damaged fasteners, and also on fasteners made from soft materials. Minimizes fastener rounding, helps to extend fastener life The TorquePlus design allows for quick and easy socket engagement to the fastener flats, not the corners Heat treated for the correct balance of strength and hardness.