Ready to change up your gearing on your Yamaha YFZ450? Or maybe your stock rear sprocket is just worn out? Check out this JT Sprocket! This is a replacement rear sprocket with 38 teeth (38T), made from ultra-durable high-carbon C49 steel. The part number is JTR1857.38 (sometimes listed as JTR185738). It's designed specifically for the Yamaha YFZ450 ATV from the 2004 model year all the way through 2018. This sprocket works with 520-size chains, which is the standard pitch for these machines. Going with a 38-tooth rear is a pretty common setup - it can give you a bit more low-end punch coming out of corners compared to the stock gearing, depending on what you're running up front. JT Sprockets are known for their quality and durability, so this isn't some cheap, thin piece of metal. It's built to handle the power and abuse of quad riding. The sprocket comes in a black finish and is brand new in its package. Whether you're tuning for motocross, trails, or just need a solid replacement, this JT sprocket will get the job done. Pair it with a new chain for the best results!