SawStop saws use a small explosive charge to jam the rapidly spinning blade into the moral equivalent of a brick wall. It destroys the explosive, the blade, and the wall, and you have to replace the whole set at a moderate expense from SawStop. This is their subscription revenue model, and of course it sometimes falsely triggers. Of course the price isn't so high that you'd rather risk losing a finger.

There are more reusable alternatives now but I don't remember what they're called. For a while SawStop was the only game in town.