Watch this Buzz-Saw stop in less than a millisecond

Would you let your kids use a Cirkular saw? With this technology i would. This technology uses conductors on the blade to sense a when to stop, perhaps when a finger crosses? It cost’s roughly 60$ to replace the break and the blade, but a finger can never be replaced. Also it looks really cool in highspeed film. This clip was taken from TimeWarp on Discovery channel.