The X-TREME Grip Sockets from SP Tools USA feature Center Drive technology, allowing the sockets to undo bolts up to 90 percent rounded off by applying pressure to the center of the bolt's flats for maximum torque. The sockets have a triple-layered chrome finish that resists corrosion, and the twin knurling ensures a secure grip even in greasy conditions. The sockets are made from chrome-vanadium steel for added strength and durability.