Stop-A-Flat Puncture-proof, Thorn-resistant, No-flat Bicycle Tubes in 12/16/20/24/26 inch wheel sizes No more wasted money replacing tubes Mounts quickly to most rims Great for bicycles, trailers and jogger/strollers Stop-a-flat tubes are "Size Specific" to a tire and care should always be taken when matching the tube to the tyre. Please note that the 1.75 sizes will fit a 1.90 standard tire.