Linear rolling-element bearings are either of the recirculating or nonrecirculating variety. In the recirculating type, bearings roll around a track with an action akin to that of a radial roller bearing with a flattened inner race. Travel is limited only by the length of the ways. In the nonrecirculating type, travel is limited by the fact that moving surface cannot be allowed to roll off the roller train. The kinematics of this geometry is such that the rollers move only half as far as the load moves, so the way or shaft must be 50% longer than the distance traveled by the load.