A printable rubber (eg NinjaFlex or other PU) tyre to fit on the standard Brompton bicycle rollers. It makes them a little larger, but not as much as the Eazy Wheels. It makes them much quieter, but of course adds no bearing.Print in Ninjaflex or other suitably squishy meterial, then stretch over the standard brompton rollers from the back, you will need to remove the wheel first.