From the manufacturer More About The Product Draper Tools 8mm Square 3/8 Square Drive Drain Plug Key is manufactured from chrome vanadium steel hardened and tempered with a satin finish. Suitable to be used on drain plugs fitted to an engine oil sumps, back axles and gearboxes. Designed to be unlocking a sump plug and allowing oil to drain from a vehicle. The product is an ideal compliment tool to any mechanics workshop.