Yokomo B10-630MA Main drive pulley for BD10 橫崛  [B10-630MA]

This might be a BD10 standard aluminum pulley. Exactly how many teeth is 20T, which places less pressure on the gear, with all the difficult finish decreases friction.

Supported Chassis
MRTC-BD10FF / MSR-BDFWD / MSR-010 / MSR-010A