Aeris A300 Dual Algorithm Nitrox Scuba Diving Computer Module and Wrist Options Aeris A300 Dual Algorithm Nitrox Scuba Diving Computer Module and Wrist Options Powered by Dual Algorithm with Deep Stop - 3 Operating Modes: Air/Nitrox, GAUGE (with run timer) and FREE (tracks calculations to allow switching between NORM and Free) Single button access to Last Dive display, 24 dive on-unit log book SmartGlo Backlighting House of Scuba is an authorized Aeris dealer