Swiss-made Thommen pocket altimeter/barometers have long been regarded as the standard by which others are judged. They use a premium aneroid capsule and a 19-jewel shock resistant movement with no lubricants to assure minimal friction and reliable operation in the most adverse environments. A range of English, metric and combined models are available with altitude capabilities to meet the most extreme requirements.
Instruments are graduated in 20 ft. (10 meter) increments with 3,000 ft (1,000 meters) per needle revolution. A small counter dial keeps track of needle revolutions. Concentric pressure scales permit reading sea level pressure and absolute pressure at altitudes as high as 7,750 ft. Dimensions are 2 1/2" x 2 3/4" x 3/4". Weight is 3.5 oz.