The bracket less running wheel can be mounted on a wire cage or an acrylic cage for easy installation.the durability that lasts for years and rotating speed stability. And the circular edge set will make it more secure, sturdy. Features: 1.The aerodynamic design reduces wind resistance, enabling wheels to rotate more smoothly. 2.Made of Clear plastic; Bearing is of good mute effect and durable in service life. 3.Whole-body washable, increase pets exercise frequency to keep healthy. 4.Strengthen pet exercise, play with pets to ease boredom. 5.Translucent material for easy viewing of pets. Specification: Condition: 100% brand new material:Plastic weight: Approx. 160g Size:(approx) Diameter:13cm/5.11inch Color:gray Package include: 1* running wheel 1*mounting accessories Note: 1. Please allow slight error due to manual measurement. Thanks for your understanding. 2. Monitors are not calibrated same, item color displayed in photos may be showing slightly different from the real object. Please take the real one as standard. .