Our #20 chain - 15 tooth front sprocket made for 50cc, 110cc, 125cc, and 140cc ATVs and dirt bikes is a quarter-pound of machined steel. This 2-1/2" disc sports a splined 20 mm" shaft bore and two 6 mm threaded (M6-10) mounting holes. The holes are 1-5/8" apart.

Specifications
Diameter: 2-1/2"
Thickness: 1/4"
Tooth count: 15
Bore (across spline grooves): 20 mm
Bore (across lands): 18 mm
Mounting hole thread: M6-108
Mounting hole distance: 1-5/8" apart
Weight: 4 ozs. (.25 lb.)