This  Propeller Balancer can be used to balance propellers, spinners, spinner back plates, ducted fan blades, wheels, and even the rotor of an outrunner motor. It has a 3mm threaded shaft with two cones that screw into place, and one end of the shaft actually floats in a magnetic field as the other end of the pointed shaft rests against a magnet. This results in so little friction that even small rotors of outrunner motors can be balanced.

Specification:
Dimensions: 55*52*44mm
Weight: 28g