The FACULX Bike Chain Tensioner is a sleek and convenient tool designed specifically for single-speed folding bicycles with horizontal rear dropouts. This essential accessory ensures your chain is securely tightened, even on these tricky bikes. Simply pull the chain, attach the FACULX tool to the bicycle axle tug fastener, and apply force. The tensioner's stainless steel construction guarantees durability and longevity, while its ergonomic design makes it comfortable to use. With the FACULX, you'll never struggle to adjust your bike's chain tension again, allowing you to enjoy your rides to the fullest.