These are hard plywood spacers for backmounting of outrunner motors.Three sizes are available to fit almost any motor on the market: 22, 30 and 40 size.


These are convenient as the length can be easily adjusted, and the can be easily sanded to provide some small addtional thrustline correction.
Finally, the wood composition helps reduce vibration, and provides some extra protection in a crash as they give way under high loads.
Once the length has been determined, stack togther and apply thin CA glue to make a solid, one-piece spacer.