The Michelin Downhill Tube is a 1.2mm thick butyl tube- heavy duty for extreme use.1.2mm heavy-duty butylItem SpecificationsWeight388gValvePrestaISO Diameter559 / 26" mtnISO Width55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71mmLabeled Size26 x 2.2-2.8"Valve LengthShort 32-40mmTube CompoundButylValve CoreFixedValve ShaftSmooth