Dive Computers for SCUBA diving come in various types, styles and sizes. Typicaly, a dive computer is used to measure and track the depth of each dive, and store this information for later viewing or downloading into a PC. Some dive computers can also help calculate air mixtures (deep diving can require using mixed gases, such as Nitrox (Oxygen Enriched Nitrogen)). Some computers keep track of decompression times, "no-fly" times and other information.