The Hot Buttons work beautifully with Matthews Doorway Dolly or the even more versatile Round-d-Round Doorway Dolly . For straight or curve track, steel, aluminum, or PVC pipe, simply remove the locking nut, self-contained wheel and tire from each axle and replace with Hot Button set and nut. Hot Buttons also make a perfect scooter dolly with just two axles and any size ordinary plywood. Combination Track/Stage Wheels #395001 are as simple to change as the Hot Buttons. These wheels have self-contained bearings designed to work on hard surfaces or 1-1/2' diameter straight track only.