The DU-BRO Tru-Spin Prop Balancer will balance model airplane props of all sizes and weights, boat props, spinners, car wheels, helicopter rotor heads, jet fans, fly wheels, etc. Each balancer comes complete with easy-to-follow assembly and prop balancing instructions. Specially designed locking cone securely centers and locks props on to the balancing shaft for utmost accuracy. Each cone is carefully inspected on a calibrator to make sure it is running true. The balancing shaft is manufactured out of hardened material and then is centerless grounded giving precision balance every time. The prop balancer's aluminum wheels turn virtually friction-free for precision accuracy.