Pro Taper Sprocket Bolt Kit If you are replacing the rear sprocket on your bike with a Pro Taper model, this is the set of bolts you absolutely need to have. Pack of 6 stainless steel sprocket bolts. 6 mm Allen-head bolts measuring 34 mm long. Includes full set of 12 mm nylock nuts. Made for Pro Taper sprockets, but fits most brands of rear sprocket.