Prevue Pet Products E-Z Roller 8" Small Animal Exercise Wheel (#90013) is sized for hamster / gerbil / dwarf hamster / mouse. The powder-coated wire mesh is a tight, diamond-pattern weave, designed to prevent feet and tails from getting caught while pets are running. Great for providing exercise options inside or outside of the cage. The wheel can stand on its own or be hung securely on mesh cage wires. Overall unit measures 8" long, 6 1/4" wide and 9 1/4" high. Wheel diameter is 8" and 4" wide.