Du-Bro 3384 - 8x1.25mm Quad Balancer Shaft (for 499)8MM X 1. 25 Quadcopter Prop Balancer Shaft Designed for use with our #499 Prop Balancer. Accurately balances quadcopter props and allows you to eliminate vibration from unbalanced props. See this current list of models this balancer shaft works with: click here! Perfectly "true" shaft with clockwise threaded end and a counter clockwise threaded end.