MX7 Tubes 26" x 0.75-1.00 (650x20-25C) (20-559 > 25-571) - Presta Valve 42mm - 155gConttnental bicycle tubes are constructed of durable, seamless butyl rubber and are inspected to ensure high quality and reliability. Seamless, and vulcanized to ensure uniform roundness and improved reliability at the valve stem. Every tube passes a stringent 100% q..