Sprockets

#25 chain sprockets have 1/4" spacing between each tooth.
The #25 sprockets are commonly found on electric scooters, gas scooters, pocketbikes, and many more.

8mm (T8F) chain sprockets have 5/16" spacing between each tooth.
The 8mm (T8F) sprockets are commonly used on gas scooters, mini choppers, and larger electric scooters.

Bicycle chain sprockets have 1/2" spacing between each tooth.
The most common bicycle sprockets are 1/2" x 1/8" and 1/2" x 3/16".  The second measurement refers to the width of the tooth on the sprocket.

Cog Belt sprockets.
The belt cog sprockets are commonly used on electric and gas scooters.

#420 chain sprockets have 1/2" spacing between each tooth.
The #420 sprockets are commonly used on gas scooters and ATV's.