Wristwatch diving computer (Nitrox, air)
EDY II Cressi-Sub

Edy II is an essential instrument for today's breath-held divers.
Its size is the same as a wristwatch's, however it is equipped with all those functions needed to monitor every single phase of breath-held diving: current depth and maximum depth, dive time, surface interval between two dives, rise rate, water temperature and many more.
In addition to all of this, Edy II is also a very good wristwatch, featuring a double time zone, alarm clock and back-lighting; it is also a tiny PC equipped with everything you need for scuba diving, by using both air and nitrox mix.