Scubapro Mantis (M1) Scuba Diving Computer Wrist Watch All dive computer algorithms factor in depth, bottom time and gas mix to calculate deco time. These enable the adaptive algorithm to adjust for each diver's experience level, age and physical conditioning. Heart Rate Monitor by visually monitoring your heart rate you can better assess your workload - real time - and promptly react to heightened stress or over -exertion. This patent-pending feature provides yet another aspect of your physiology that can be factored into the workload algorithm. Can be a valuable aid when exercising or lap swimming in shallow water.