Design rrquires improving
These cat wheels are very noisy that scares most of our cats from using it. The reason for it being as noisy is due to the fact there is no adjustment for the small rubber wheels that that run on the inner side of the main running wheel, and the clearance is too tight between the plastic arms holding tgese small rubber wheels, that results is some of the wheels not touching the main running wheel, allowing it to rub on the plastic base itself. A simple remedy for such an expensive item