This great Aqua Lung i750TC Scuba Diving Hoseless Air Integrated Bluetooth Computers features: Primary Use: Scuba Diving, Snorkeling, Freediving/Spearfishing Make: Aqua Lung Model: i750TC PC link: Bluetooth Depth Rating: Mounting Type: Wrist Watch Color: Black Special/Unique Features: 4 operating modes: Air, Nitrox, Gauge (with run timer), and Free Dive (tracks calculations to allow switching between DIVE and Free on the same day) User changeable battery and data retention. Maintains settings and calculations between battery changes Backlighting. For easy reading in low light Audible alarms and additional high-visibility LED warning light for additional safety User-updatable software gives access to the latest features and upgrade (must purchase optional download cable) Defects: None SCUBAPRO MERIDIAN:Intelligence at Hand Engineered by divers for divers, the SCUBAPRO Meridian performs advanced functions in timeless style above and below the surface. Use Meridian as a multi-function wrist watch, dive in SCUBA, APNEA or GAUGE modes-SCUBAPRO delivers the best. Displays are visually clear and easy to navigate. An intuitive +/- push of a button leads you to more advanced information and data. Housing in highest marine grade 316L stainless steel with two-toned brushed finishing, for heavy duty longevity with designer looks. MERIDIAN|COMPUTER: SCUBA|APNEA|GAUGE SCUBA The Predictive Multi-Gas algorithm lets you enjoy the full benefits of carrying high oxygen concentration mixes (21%-100% O2 compatibility) in addition to your main breathing gas. Meridian calculates the decompression schedule for all possible gas combinations and in case you don’t switch to the new mix, it adapts the calculation accordingly. Complete Dive Planner calculates not only no-deco time but also total ascent rate, settings, workload, previous dives etc. and includes both gases if applicable. Meridian’s algorithm ZH-L8 ADT MB reduces the formation of micro-bubbles, making diving safer. By choosing a MB level between L0 and L5, you adjust the algorithm conservativeness, allowing you to either take up less nitrogen or off-gas more quickly The unique integrated Heart Rate Monitor senses your effort, incorporates it into the workload calculation and then adapts the decompression algorithm. The result is safer diving, because each diver is unique, because each dive location and situation is different. PDIS optimizes your dive in complete security for a safer and more pleasurable adventure. The PDIS (Profile Dependent Intermediate Stops) option calculates an intermediate stop based on how much nitrogen uptake your body has endured, taking into account your current dive, previous dives and breathing mixes. PDIS is a unique scientific application for safer, more optimized decompression. No matter what kind of diving you do, you candownload your profiles, bookmark comments and change warnings/alarms/settings via SCUBAPRO LogTRAK software with the optional communication crad