Super Pet's Small Comfort Wheel is perfectly sized for your healthy hamster, motivated mouse, or jogging gerbil. The Comfort Wheel features a safe, solid running surface, quiet operation and a tail-safe 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. Available in four cool colors including blue, teal, lavender and purple.5.5 Diameter - UPC: 45125613827