*****PLEASE ENSURE CAGE / CAGE DOORS ARE 14 INCHES TALL OR MORE! Exotic Nutrition s Silent Runner 12 Regular Wheel is the most innovative wheel on the market for its safety features and whisper-silent spin. MEASURES: 13.5 tall on stand 12 wheel diameter 3.5 wide track 4 diameter openings. FEATURES: ✔ SAFE - The axle-free design eliminates a dangerous center bar reducing the risk of fur/tail entanglement pet wrap-a-round curvature of the spine and other injuries. ✔ SILENT - Innovative dual ball-bearings create a whisper-silent spin. ✔ AUTOCLEAN TRACK - Allows feces urine and other pet debris to drain from the wheel. This track requires much less cleaning than other solid-surfaced tracks and increases ventilation within the wheel. ✔ NON-SLIP - Running tracks are textured for excellent grip. ✔ SANITARY - Wheel completely disassembles for deep cleaning no nooks for feces to hide in. ✔ SECURE - Closed off design with front plate for privacy safety and containment. With natural bean-shaped openings and a pet-preferred solid black rear wall. ✔ HIGH QUALITY - Wheel is made of high-quality plastic. ✔ JOINT PROTECTION - The stand allows for give protecting your pet from joint pain caused by running on a hard fixed surface. ✔ IDEAL FOR - Sugar Gliders larger Hamsters and other similar small animals (not suggested for chewers).