The advantages of the Continental Unitube system. Multi-size tubes allow greater compatibility with more tire sizes, and fewer tubes. Unitubes are available in both Schrader and Presta valve tubes. Presta valves are available in a variety of lengths. All tubes are seamless and mold-cured (vulcanized) to ensure uniform roundness and improved reliability at the valve stem.Each and every tube passes a stringent 100% quality control inspection.