Feature: 1. Avoid Chain Skipping: The inner tube of the frame can adopt a single speed chain tensioner, which can effectively avoid chain skipping and ensure safe and stable cycling. 2. Adjust Tightness Of Chain: Bike chain adjuster is suitable for folding bicycles, single speed bicycles and stationary bicycles, used to adjust the tightness of the chain. 3. Fine Workmanship: Precise structure, exquisite craftsmanship, attention to detail, an important tool for adjusting bicycle chains, equipped with screws for easy operation. 4. Multiple Applicable Occasion: Light weight, no extra burden on the bicycle, easy to store and carry, can be easily put into your bag, suitable for home, bicycle repair shop, travel, etc. 5. Aluminum Alloy Material: Bicycle chain tensioner is made of high quality aluminum alloy material, firm and sturdy, stable and wear resistant, durable for long term use. Specification: Item Type: Bicycle Chain Tensioner Material: Aluminum Alloy Application: Folding bicycles, single speed bicycles and stationary bicycles. Function: Adjust the tightness of the chain Size: Screw: Approx. 24 x 20 x 4mm / 0.9 x 0.8 x 0.2in Chain Tensioner Accessories: Approx. 23 x 11 x 5mm / 0.9 x 0.4 x 0.2in, 20 x 11 x 11.5mm / 0.8 x 0.4 x 0.5in . Package List: 2 x Chain Tensioner Accessories2 x Screw Note: Please allow slight error due to manual measurement. Thanks for your understanding.