High Quality Steel Split Sprocket for 420 Chain. 6 bolt pattern measuring 5-1/4" Across center to center. Split for easy gear changes. No need to remove the axle on your Mini Bike or Go Kart to change the Gear Ratio. The Hub Pictured is not Included. For reference 60 tooth diameter is 9 3/4 inches. 40 tooth diameter 6 5/8 inches. These are Heavy Duty and Wear resistant. Great For Mini Bikes and Go Karts. Fit Most Racing Go Kart Sprocket Hubs.