This is the Du-Bro 6mm Quadcopter Propeller Balancing Shaft.
FEATURES:
Designed for use with the Du-Bro #499 Prop Balancer (DUBQ0130)
Accurately balances quadcopter props to eliminate vibration
Works with all 6mm threaded propellers like those used on the DJI
Phantom and more
Material : Aluminum
INCLUDES:
Du-Bro 6mm Quadcopter Propeller Balancing Shaft ONLY