Dan Bragg and the team at Bragg Watch are engineers and technicians interested in military technology and equally passionate about orienteering - the sport of land navigation. The team got together to invest in and to develop both an affordable tactical watch, and an orienteering instrument, and the Black Ops Chrono was born.\nThe Black Ops Chrono utilizes sensors to determine elevation, environmental pressure, and current heading for onboard digital altimeter, barometer, and compass, also known as A-B-C instruments. The altimeter provides elevation data to accurately monitor ascent and descent. When used in conjunction with topographic maps, knowing your elevation can help guide you both on and off the trail. The most common type of altimeter is barometric, which determines altitude by measuring air pressure. Bragg's barometric altimeter measures altitude more accurately than GPS. The barometer is also used to predict weather changes by showing trends in air pressure. It works best when you are not changing location for several hours such as when you are camping. The digital geomagnetic compass provides your heading, or direction of travel, and it can be used when you are still, or walking slowly. The accuracy of these sensors is dependent on calibration. While the electronic compass is factory calibrated, follow the simple steps in your Bragg Watch Owner's Manuel to calibrate your Black Ops Chrono electronic compass before stepping out into the wilderness.