Yukon takes spool lockers to a whole new level. Made from high quality 4130 Chromoly steel, this ain’t no ordinary spool locker. It’s high quality material and construction ensures high strength and a long life. The Yukon Spool Locker features a solid, one-piece construction that transfers 100% power to both tires at all times. They are a simple and inexpensive way to lock up your differential for maximum traction. Not recommended for on-road use.