Set includes thermoplastic gears, 2 have 3/8" hole and one has 1/8" hole. Largest is a double, 2" diameter with 31 teeth and 1-1/8" with 17 teeth. Next size is a double, 1-5/8" diameter with 40 teeth and 1-3/8" diameter with 22 teeth. Next one is a single, 1-1/4" diameter with 30 teeth. Matched belt is 4.5 inches diameter. Unused.