Atmospheric Data CenterADC Ridge is a classic hand-held altimeter/barometer which shows both the absolute barometric pressure as well as the altitude above sea-level and height differences. The ADC Ridge is easily calibrated by turning the altimeter scale ring.The ADC Ridge comes with a click-on lanyard and the design and friction treatment of the body provides a perfect hand-fit both with and without gloves. Battery free Altimeter Barometer