I have a 4WD Volvo that likes to have 4 worn tires at the same time. If you don't change all the tires at the same time, you run the risk of damaging the transmission. It's off track - I've had 4 tires in the last quarter of their life but had about a year left. Then a nail hit one of those tires - still threaded but close to the sidewall. Took it to the store and they didn't want to take responsibility for the repair as they put the patch on the inside which is not possible in this region. So I went to Amazon and found this product. Thought I'd give it a try, it was a thin nail and I spent $700 on a new set of tires for a car I no longer drive (working from home thanks to the pandemic), removed the nail with pliers, loaded a tool - and tries to push it in whole. Damn, these tires are tough! It took me some time and a lot of effort to enforce it. Then I just pulled it - it was easy and the rubber cord stuck out - cut with snipers and done. I filled the tire with air and let it sit overnight. . The next day I checked - exactly the same value as the day before. With the nail I lost about 2-3 psi overnight. Now it was zero. Car started as usual. I checked again the following days - no changes. I checked again a week later - the ideal print. I checked again a month later - the ideal print. So this thing works. Not sure I'll be using it on a large scale - I put in a small puncture repair (2-3mm) 1/8 which turned out beautifully.