​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. Features: Built for the modeler who expects the very best 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 Precision-machined rotating wheels to assure perfect balance easily Unique over/under set-up option accomodates even large-scale props Dubro separetly offers optional quadcopter balancer shafts for both 5mm DUBQ3380 and 6mm DUBQ3381 Item name: Prop Balancer Suitable for: RC Multi-Rotors, RC Quadcopter, RC Hexcopter, DJI Phantom, DJI Inspire, DJI F450, RC Airplane, RC Helicopter Material: plastic and metal Package Information: Package size: 16 * 9.5 * 4cm / 6.3 * 3.7 * 1.6in Package weight: 334g / 11.8oz gift box package Package List: 1 * Tru-Spin Prop Balancer (unassembled) 1 * User Mannal