Kaytee's Small Comfort Wheel is perfectly sized for your hamster mouse or gerbil. The Comfort Wheel features a safe solid running surface quiet operation and a intail-safein design allowing pets easy entrance and exit. Every Comfort Wheel comes with a heavy duty wire stand and a 2-way attachment clip so the wheel can be used either free-standing or clipped to a wire cage. Wheel is 5.5in diameter. Available in assorted colors.