[Design]: Exercise Bike Resistance Knob f most bikes Exercise Bike. [Material]: Made of plastic metal material, durable functional. [Feature]: The knob small ptable, will not scratch your hs due to winding. [Easy to install]: The knob is easy to use quick to install, it will not take up too much time f you, it is very convenient. [Applications]: The Bike Knob Exercise Bike Accessy is widely suitable f strength fitness equipment, exercise bikes, etc. Type:10 Gears or 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 different displays may cause the col of the item in the picture a little different from the real thing. The measurement allowed err is 1-3cm.