The 6 inch (152mm) aluminum Mecanum wheel is comprised of a series of rollers, mounted so that their axis of rotation is 45° to the axis of the main wheel. As the wheels rotate in sync, the vehicle moves forward or in reverse normally, but by spinning pairs of wheels in opposite directions, the rollers enable sideways movement. Put it all together and you can move forward, backward, laterally, diagonally, or spin in a circle. Also included are twelve extra bolts (60 mm long) for bolting on the 6mm Nexus aluminum wheel hub or the 8mm Nexus aluminum wheel hub.