Special Notes:Notes for Kit Item: Primary Drive Rear Aluminum Sprocket 49 Tooth BlueYou must use a tapered style sprocket bolt (part #1096010001) for this sprocket Compatible with Yamaha WR250R. -Rear Aluminum Sprocket made from 7075 T-6 heat treated Aluminum. -Come with self-cleaning grooves. -All match original equipment exactly for perfect fit and size. -The ORM O-Ring chain provides outstanding durability and long wear characteristics making it perfect for motorcycles and ATV's. -Features solid bushings with high quality pin material, O-rings and lubricant. -The unique design and profile of the chain ensures durability, and decreases wear on chain guides and swing arm rub plates. -Average tensile strength 7,850 lbs. -Clip style Master-Link included.