Weapons light that turns on automatically when you unholster?

I thought I saw a weapons light for a pistol that automatically turns on when you unholster. If I remember correctly, you glued a magnet on your holster and when it did not sense the magnet, it turned on. Any ideas who makes a weapons light for a pistol that automatically turns on? via /r/CCW http://ift.tt/2nzNCfn