The Zen is a stylish instrument that can be worn at the office, on the town or in the ocean - anytime, anywhere the Zen is your go to instrument. The IQ-900 can be operated as a Watch, Air computer, Nitrox (EANx) computer, Digital depth gauge/timer or as a Free dive depth gauge/timer. The Zen's large alphanumeric and backlit display allows for high legibility in or out of the water, although its size is that of a normal style watch! In addition to offering the latest comprehensive computer features, the Zen addsa Deep Stop function for enhanced safety. Deep Stop Function The Zen computer features an optional deep stop function for additional safety. The deep stop mode is activated when a dive exceeds 80 FT (24M) for more than 1 second. Upon ascent past 50 FT (15M), the computer will display a Deep Safety Stop screen and the recommended stop at 40 FT (12M) for a period of 2 minutes. This deep stop is highly recommended as additional opportunity to off-gas, but is not mandatory. Click below to view a series of tutorial videos for the Tusa Zen IQ-900 Tusa Zen IQ-900 overview Tusa Zen IQ-900 Settings overview Includes now FREE a Digital online class to get the most out of your dive computer. Click here for details