GoolRC OCDAY Tru-Spin Prop Balancer for RC Helicopter Multirotor Airplane Manufactured out of hardened material Balances air props of all sizes and weights, boat props, spinners, car wheels, heli rotor heads, jet fans, fly wheels, etc. Securely centers and locks props on to the balancing shaft for utmost accuracy Each balancer comes complete with easy-to-follow assembly and prop balancing instructions Completely adjustable propeller balancer