JT Sprockets Steel Rear Sprocket Yamaha YZ 125 250 1999 - 2021 YZF 250 2001 - 21 YZF 426 2000 - 2002 YZF 450 2003 - 21, 51TJT Sprockets is the world's leading manufacturer of aftermarket sprockets, constantly raising the industry's standards for quality and service. SC Lightweight Steel Rear Sprockets The new standard in steel rear motocross sprockets. A unique self cleaning design keeps the contact area clean from dirt and mud while significantly reducing weight. Made from heat induction hardened C45 steel which lasts up to six times longer than a 7075 aluminium sprocket