SUPERSPROX REAR STEALTH SPROCKET ALU/STL 51T-520 BLU KTM/HUS SUPERSPROX P/N: RST-990-51-BLU Interchangeable P/N: 108-990451 Fitment: KTM/HUSQVARNA 125/150/250/300/350/450/500/501 - Message seller for direct fitment. Features: The only dual material rear sprocket available for both street and off road applications Steel teeth last up to 3 times longer than aluminum 7075-T651 Aluminum core, lighter than steel CNC machined, providing perfect fit on the wheel Larger tooth radius reduces chain friction and extends chain life U. S. and European patented Please ensure fitment prior to purchase. Item will come in original packaging. If you have questions, please contact the seller. Not responsible for improper or ill fitment due to incorrect year, make & model given by buyer upon purchase.