The industry standard comes in all sizes Premium-quality Bontrager Standard butyl rubber tubes feature a 0.9mm wall thickness for the perfect balance of weight savings and durability. - 0.9mm wall thickness - Equipped with removable valve cores - 100% inspected for guaranteed quality - Best value 27-inch tire size equivalents - 700c x 28 - 32 also fits 27 x 1-1/8 - 1-1/4 - 700c x 35 - 44 also fits 27 x 1-3/8 - 1-3/4