Check the listing for details. 🔥🔥Stationary Under Desk Exercise Cycle Pedal Trainer *Missing Tension Knob. Condition: Used. Listed at 34.99 USD. This stationary under desk cycling trainer is used but in good condition. It still has a lot of life left. It is missing the tension knob that goes in the back. It can be used without it but I’m assuming to tighten the resistance you will need a replacement knob. Make sure you look at ALL photos. What you see in the photos is what you will get. If you have any questions feel free to contact us. Thank you! We appreciate all our customers, new and returning, and pride ourselves on maintaining a great reputation and track record as eBay sellers! Please reach out to us with any issues or concerns before escalation as we will do whatever is necessary within our power to correct or remedy your situation and find a solution all parties can be satisfied with.