L had ContiSeals on my Alhambra a few years back and got a screw in a rear at around 2,000 miles, I watched them as they took it off, inside on the back of the tread is something that looks like a strip if green “blu tac” thats a few mm thick, if you get a screw/nail etc up to 5mm diameter and remove it the sealing compound will expand to fill the hole.
I thought it was a permanent seal but according to their info once this has happened you have to get the tyre replaced as soon as possible thus rendering the tyre scrap even though it could still have loads of tread left, very bad for the environment and your wallet, I also found them to be low grip and would break traction with the slightest throttle and were down to wires under 10k.