Gas and electric scooter sprockets used in both chain and belt drive scooters, pocket bikes, atvs, go karts, and electric bicycles.
#25 chain sprockets (1/4" spacing between each tooth): Used on gas scooters, gas skateboards, electric scooters, and many others.
8mm chain sprockets (8mm spacing between each tooth): Used on many 49cc & 52cc gas scooters, gas pocket bikes, and mini choppers.
Belt sprockets are usually designated by the pitch (distance between cogs) plus number of cogs (or teeth). For instance, an M5-15 belt sprocket has 15 cogs around the axis, each cog being 5 mm distance between it and its nearest neighbors on either side.