The Reedjet belt driver comes complete with any 1-1/4 (1.25) gear sleeve 18, 19, 20, 21 or 22 tooth. Sleeve can be changed simply by removing the nut and washer, sliding the sleeve off and replacing with another. Hegar recommends applying with blue Locktite on crank nut. 0.750 is the major inside diameter of the taper, please confirm with your crank before ordering.