Michelin c4 airstop butyl mtb tubes 6 pack our pack of 6 airstop inner tubes means you save over buying the same tubes individually this is an economical and long lasting tube with good puncture resistance the 09mm wall gives optimum puncture protection and butyl provides better resistance to friction features weight 196g valve presta valve length 40mmsize 26 x 16 to 21buy michelin wheels and tyres from chain reaction cycles the worlds largest online bike store