A circular sleeve is disclosed which fits into a lengthwise bore in a slider to provide a return passage to make sure of smooth rolling in a slider downsized or compact in length. The sleeve is inserted with leaving circular clearances inside the lengthwise bore in the slider. The sleeve has a bridged beam portion and cantilevered beam portions all of which may undergo elastic deformation under urging or impact force caused by rollers while rolling through the return passage. The bridged beam portion is flanked by support beam portions forming the outside circular surface of the sleeve and the cantilevered beam portions are fastened at their inward ends to a middle support beam portion and freed at their outside ends to bend or warp.