The Tamiya Pinion Gear Set 20T/21T is a set of RC Parts. They are 48 pitch metric 20 tooth and 21 tooth gears. The number of teeth is stamped on the pinion so they cannot be confused which is which. They are made of aluminum. Includes One 20T pinion gear (48 Pitch) One 21T pinion gear (48 Pitch) Two Grub Screws Manufacturer: Tamiya Model: 50356 Pinion Gear Set 20T/21T 48 Pitch