Bests & Worsts Reviews from Amazon

I got a couple of these a coupld weeks back after watching a Mythbusters episode about submerged cars. For my wife the unit is small and easily added to here key ring. I hung mine from the seatbelt in my car. I had some tempered glass laying around my garage, so I gave it a quick try. It worked as expected. With just a little bit of pressure the glass was punctured and immediately shattered. I highly recommend this device, especially give its low price.