Since the invention of the air-filled tire by John Dunlop in 1888, the bicycle tube has kept the air in the tire. The Fischer tubes are made from robust and flexible rubber. Tubes form the basis of relaxed cycling: When the tube fits perfectly on the rim and, when optimally inflated, forms a unit with the tire, it almost rolls by itself. Of course, the elastic tube can also be stretched a bit to fit a larger rim or compressed to fit a smaller rim, but both options can affect the riding behavior and the lifespan of the material. Therefore, it is important to buy exactly the type that the rim requires, including the correct valve for the existing hole. ETRTO standard: 40-507, 44-507, 47-507, 49-507, 50-507, 54-507, 57-507. Inches: 24 x 1.5, 24 x 1.625, 24 x 1.75, 24 x 1.85 / 1.9, 24 x 1.85, 24 x 1.9 / 2.0, 24 x 2.0, 24 x 2.125, 24 x 2.10. The elastic material covers all the tire sizes mentioned above.