Zipp Tangente Inner Tube 0.60mm thick to optimize durability 37mm valve stem length Lightweight aluminum valve body with removable Presta valve core When installing Zipp Tangente tubes (37mm valve stem) on Zipp wheels, the following valve extender is recommended: PU9911, 27mm (1 gram) for 303 model wheels PU9912, 41mm (2 g.) for 404 For use with Zipp Tangente Aluminum Knurled Valve Extender