ColorBlue Target Species Mouse, Gerbil, Hamster 6.7" DIAMETER - The wheel encourages healthy exercise for hamsters, mice, gerbils or other small animals. SILENTLY - Silent spinner and no noise, The wheel rolls smoothly and silently. STURDY - No need to install, placed directly on the flat floor of your pet's home. The wheel can be used either free-standing, with the suppiled stand, or be attached to wire hamster homes. EASY TO CLEAN - To clean the wheel use only mild, soapy water and a non-abrasive cloth or sponge. TIP: If the wheel becomes noisy or difficult to turn then check the metal disc in the centre of the wheel. There should also be a slight gap between the back edge of the grey plastic centre and the inside face of the wheel.