This well designed plastic gear set has a multi-purpose assortment that will provide a thousand uses for model builders and hobbyists. Included in the set are: 20 double gears 50/10 teeth 2.9 mm hole 20 double gears 50/10 teeth 3.1 mm hole 8 pinions 10 teeth 1.9 mm hole 4 set collars * 20-part