What are these pads on the bottom of my furniture?

I'm putting together a 7 piece desk/hutch set. Each base unit (the heavy part with drawers and legs) has a shelving unit that sits on top of it. On the underside of the shelving units are these small dots, about the size of a dime. They have the consistensy of Mole Skin cloth and are very thin (about 1/16 inches thick). They are not felt. And I've been to every store and website i can imaging and cannot find a replacement. I'm only finding felt pads, which don't do the job because felt slides and these don't so they hold the shelving unit onto of the base better. Anybody know what those are, and where I might be able to find replacements?