The Spartan Lockerby USA Standard Gearprovides reliable traction at a low cost. Give your vehicle great traction and save some cash. Choose a Spartan Locker for better traction. The Spartan locker by USA standard gear is a mechanical locker that replaces the spiders in a standard case. The Spartan locker’s design does not use the thrust washers and has a revolutionary spring and pin design that makes installation a snap! The couplers are made from 9310 steelfor added strength. Each Spartan locker carries a one year warranty against defect. This unit uses the factory side gears.