When you can't even see a part, you might forget about it, but it doesn't mean it's not important. Flat tires are probably the most common bicycle failures. Many times, flats are caused by the rims, specifically the lack of protection from the rim's sharp edges. The Odyssey rim strips are made from nylon and are designed to cover the entire inner width of the rim, protecting the tube from the spoke holes, vent holes and any other sharp edges that can bring your session to an end. If you forget about them, that means they are doing their job. Specifications Diameter: 20" (406mm) Width: 30mm Quantity: Pair