Challenge Latex Tubes 48mmChallenge produces the only seamless 'one piece' latex inner tubes on the market providing a smooth, balanced ride with no pucker or bump like those found on other tubes. Latex tubes are lighter, thinner and more flexible than a butyl tube, increasing your comfort, lowering your rolling resistance, and helping to prevent flats. The tube also includes a removable core Presta valve making them compatible with both inline and external valve extenders.