Although hard to find when they get batted under furniture (there is still one wool ball hiding somewhere in our small abode), these small, tightly packed wool balls roll beautifully over carpets, rugs, and, of course, hard surfaced floors. They bounce off vertical surfaces and keep our 4 year old feline busy for several minutes at a time - which is a good time duration for a young hunter. Since the surface is not smooth like plastic, it easily holds catnip scent when rubbed with same. This enhances our cat's play experience. Thank you for carrying a great product which is really nicely packed for storage of the waiting balls - for when the one in play gets lost. So far, none have ever worn out! Even after being "disemboweled," And, of course, the cat often "helps" me - or rather supervises me as I get my exercise retrieving the ball from under the couch or a corner where it is more fun for me to pick up and set the ball rolling for him to chase rather than for him to bat it again.