Tube Challenge 700C x 33-40C Seamless Latex Presta 48mmTube Challenge 700C x 33 40C Seamless Latex Presta 48mm Challenge Seamless Latex Inner Tubes are 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 comfort, lowering rolling resistance, and helping prevent flats.