[Design]: Exercise Bike Resistance Knob for most bikes and Exercise Bike. [Material]: Made of plastic and metal material, durable and functional. [Feature]: The knob small and portable, will not scratch your hands due to winding. [Easy to install]: The knob is easy to use and quick to install, it will not take up too much time for you, and it is very convenient. [Applications]: The Bike Knob Exercise Bike Accessory is widely suitable for strength and fitness equipment, exercise bikes, etc. Type:10 Gears/8 Gears Colour:Black Material:Plastic Package Contents: 1 * Exercise Bike Resistance Knob Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.