New AERIS A300 Personal Scuba Diving Wrist Computer - Powered by Dual Algorithm with Deep Stop 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) 3 Operating Buttons with intuitive Switch between up to 3 Nitrox mixes to 100% O2 with individual PO2 alarms Free Online Class Sold Separately