The Breitling Emergency E7632110.I500.138E was originally designed for pilots and aircrews. It is a watch with a built-in micro-transmitter broadcasting on the 121.5 MHz aircraft emergency frequency and is designed to complement the distress signalling equipment of any aircraft. Following a crash the 'Emergency' will broadcast a signal on which rescuers can home in. The transmitter in this E7632110-I500-138E is activated (for 48 hours) by unscrewing a protective cap and pulling the antenna out fully. Over flat terrain or calm seas, the transmitter signal has a range of about 160Km (assuming the search aircraft is flying at an altitude of 6000m). This E7632110 I500 138E comes in a titanium case with a sapphire crystal.