CNBTR Model Rotatable Coupling Motor Connector Universal Joint Coupling 6x6mm With Spanner Pack of 2 Material: Iron plating Fixed aperture: M6 Dimension: 23 x 11mm / 0.91 x 0.43"(L x Dia) Allow the angle between the two axes within a limited range vary with operational needs. The metal universal joint is suitable for straight shaft motors,use for model cars, model ships, robots and other types of metal transfer.