This is the One-Way bearing for the HPI Nitro Star 21BB engine.
** Also fits the Roto Start for the Savage.**
This One-Way Bearing allows the recoil starter to grab
the crankshaft to start the engine and spin freely in the opposite direction.
One one-way bearing
One installation instruction sheet
Installing in recoil unit
Overall Length: 12mm (.472")
Hex Width: 12mm (.472")
Inner Diameter: 6mm (.218")