Wodent Wheel has an 8 inch diameter, 2.6 inch wide track, and 2.1 inch entry holes. Overall height (on the stand) is 9.1 inches. Suggested for hamsters, sugar gliders and larger mice. Color - Black Panels & Green Track. You may also wish to consider the new Silent Runner Wheels which have dual center ball bearings to allow the wheel to spin freely, and do not have the center axle like the Wodent Wheels which can cause injury. We do offer inexpensive Axel Guards and Glider Shields which are safety accessories to cover the center wheel axle. If not properly maintained, Sugar gliders can get their tail fur stuck to the center axle. The Axle guards and Glider Shields can prevent this. Although Wodent wheels have been a standard in the past, the newer Silent Runner Wheels are strongly suggested for their innovative safety and design features. Silent Runner Wheels are safer, smoother running, quieter and allow for direct cage attachment with optional cage attachment hardware ... features not offered with Wodent wheels.