The panaracer supertube 26x16 presta valve tube is 50 percent thicker than regular butyl tubes for staunch flat protection made of a super spongy compound the super tube is the only choice for dh or anytime you canrsquot afford a flat itrsquos the only tube out there that can keep on keeping on panaracer supertube 26x16 presta valve tube features sizes 26rdquo x 16 21 or 21 25 valves presta or schrader weight 230g 16 21 or 360g 21 25