Aerobatic propellers weigh more than non aerobatic propellers, so I was looking for a way to reduce that impact on the plane. The Sky Dynamics Featherweight Flywheel drops around 3 pounds from the very front of the engine.

This is installed at the front of the engine. The starter engages the teeth of this gear in order to spin the engine while in the startup process. The pulley is used to drive the main alternator.