Features: 1.Wide Application: The 420 chain front rear sprocket kit is specially designed to fit 50cc to 125cc dirt bikes, mini bikes, ATVs and 4 wheel go karts. 2.Sprocket Size: This sprocket drive gear is 0.235in thick and has 17T. Center mounting holes are 1.18in apart and are compatible with 17mm engine countershafts. 3.Heat Treatment: To make the sprocket stronger, the sprockets are heat treated, which increases the strength of the sprocket, making it resistant to wear and tear very well. 4.Gear Curve Design: The sprockets also have an upgraded gear curve that helps reduce transmission friction, which helps extend the life of the chain. 5.Ideal Replacement: This kit is designed to replace the old one in different power sport vehicles using 420 chain sizes. The front sprocket is supplied with mounting screws. Specification: Item Type: 420 Chain Sprocket Kit_x000D_ Material: 45 Steel + Steel Alloy_x000D_ Rear Sprocket: 420 37T 155mm_x000D_ Front Sprocket: 420 17T 73mm_x000D_ Application: Complete chain and sprocket set designed to replace old damaged chain and sprocket sets from originals to get your riding going again._x000D_ Fitment: _x000D_ Fit for 50, 70, 90, 110, 125cc Dirt Pit Bike and Mini Bikes, ATVs, Go Kart _x000D_ Replacement for Coolster _x000D_ Replacement for Apollo _x000D_ Replacement for SSR and more Note: To avoid receiving the wrong product, please take the time to check and confirm the correct shaft, chain size and number of teeth before placing an order