A. This folding bicycle gear and brake cable housing is designed for mountain and road cycling. It's a good option to enhance cycling safety and experience. B. It comes in two specifications: a 4 - millimeter gear cable housing per meter and a 5 - millimeter brake cable housing per meter, which can meet the requirements of different types of bicycle gear and brake systems. Whether you're a road cycling enthusiast seeking speed or a mountain biker loving challenges, you can find a suitable cable housing to ensure a smooth ride. C. The cable housing is made of relatively good - quality materials and is sturdy and durable. It can withstand various pulls and frictions during cycling and is not easily damaged, providing stable and reliable support for the bicycle's gear and brake functions. D. It has a wide range of uses. The inner cable installed inside the housing can effectively reduce friction, making gear - shifting and braking operations more sensitive and accurate. Using this cable housing can make the bicycle shift gears more smoothly and the brakes respond more promptly, greatly improving cycling safety and controllability. This cable housing is suitable for various folding bicycles. Whether it's for daily commuting or long - distance cycling, it can be a practical accessory for your bike, making your cycling journey more relaxing and enjoyable.