The DU-BRO Drone/Quadcopter prop balancer's aluminum wheels turn virtually friction free for precision accuracy. The Du-Bro Tru-Spin Prop Balancer will balance drone props of all sizes and weights. Each balancer comes complete with easy to follow assembly and prop balancing instructions. A truly precision instrument built for the modeler who expects the very best. #3396, 3380, 3381, 3383, 3384- Specially designed balancing shaft with left and right hand threads. For Drone/Quadcopter Props. Balancing shaft is made of CNC machined aircraft aluminum for a precision balance. Some very popular drone models such as the DJI Phantom 4 include unique prop hub that will not work with traditional balancers. DU-BRO has a solution for these propswith ourcenterless ground Friction-Fit prop balancing shafts that works with the popular #499 or #3396 Tru-Spin Prop Balancer.