420 18T Motorcycle Front Engine Sprocket 17mm Compatible with 50cc 70cc 90cc 110cc 125cc 140cc 160cc Dirt Bike, Mini Bike, ATVs, Go Kart SprocketSize: 420-18T | Number of Items: 1Specification: 420 18 Tooth 17mm Inner Diameter. This product is applicable to 420 Chain Master Link / Countershaft width 17mm. The method to distinguish 420 and 428 sprockets is to measure their thickness. Package includes: 1 sprocket, 4 bolts, 2 mounts, 1 wrench, 1 420H link head. This sprocket is designed to fit 50cc, 70cc, 90cc, 110cc, 125cc, 140cc, 150cc dirt bikes, mini bikes, ATVs, and 4-wheel go karts. Material: 45# Steel, offering high strength and deformation resistance. If you're hearing squeaking sounds from your chain while riding at low speeds, or feeling vibrations or hearing clicking sounds when rolling your bike forward or coasting to a stop, it's a good idea to check your front sprocket. When this part starts to malfunction, replacing it right away is recommended. Dimensions: 4.2 x 3.7 x 0.8 inches.