Gotta have a way to get the power from the motor to the drivetrain. Sounds like the worlds supply of 5mm pinions evaporated once the Mamba Monster came out. Manufactured from hardened steel. Most common use will be for the 1/8th scale conversions.
11T Steel pinion for 1/8 Buggies
MOD-1
5 mm shaft hole
Available in 11T, 13T, 15T, 17T, 19T, 21T and 23T.