<p>Before purchasing an inner tube, please check whether the original inner tube is an American valve or a French valve, and its size, so that it can not be installed after purchase. This inner tube is made of high-quality butyl rubber and is designed for 26-inch mountain bikes. It has an American valve and French valve option, with valve lengths of 32L, 35L, and 48L. The fetal wall thickness is 0.87 mm. Please note that the inflation of the inner tube alone will be greater than that of the outer tube, which can affect the service life of the inner tube. The inner tube can only be filled in the outer tube, which is the correct way to use it.</p>