Silent Spinners work two ways: free standing or attach directly to any wire cage. Features a high-quality plastic running surface is safe and comfortable for your furry friend's feet. Best for mice and dwarf hamsters. Wash with a mild soap solution, rinse thoroughly with clean water to ensure the removal of soap residue, then dry completely. Specially designed for quiet spinning Encourage healthy exercise Available in assorted colors: Blue, Green, Purple, Red 4.5 Inch diameter