you have to get 1 inch inner diameter pvc (from any hardware store), and lathe or dremal(hard to do) it out untill it fits on the micro wheel. then just cut to length. i think my OD(outer diamter) on my micro rs4 wheels are just a hair under 1 1/18th inch. it takes a pretty steady hand and some luck to get the inside round if you are using a dremal. it takes all of about 5 mins to do it in a machine shop (and it turns out much better). hope that helps. if you have any more questions, just ask.