Features: Make with high strength aluminum alloy, this bicycles chain fastener ensures durability and corrosion resistance. Not easy to fade, more beautiful. Effectively prevent the chain from falling off frame and damaging the surfaces of frame. Specifically designs for folding bikes, this bike chain tensioner help adjust the chain tightness to prevent derailment effectively. Exclusively designs for rear fork bicycles with a 10mm/0.39inch rear opening structure, ensuring a perfectly fit and maximums stability. Easy to install. It is a perfect replacement for your old or broken one. Specifications: Component: Metal Color: Black/Red/Blue color/Gold/Silver Size: As Shown in the Picture Package Includes: 1pc Bicycles Chain Tensioner note: Please allow 1-2cm errors due to manual measurement, make surely that you not mind before order. Due to difference between different monitors, the picture may not reflect the actual color.