This stuff does work! I bought a bottle of this for "emergency" purposes, and tested it out to see if it really worked. It does. Goes in through the valve stem in a pinch, and sets quickly. It will quickly fix a tire, and get you going. It however leaves your tires out-of-plum, and generally calls for them to be replaced anyways. This just prevents you from getting caught out in the middle of nowhere. Worth keeping in that emergency bag.