This is an excellent product that combines an altimeter, barometer, thermometer and compass in one. It is made of high-quality materials and is tear-resistant. The shell is pressure-resistant, cold-resistant and heat-resistant, suitable for various harsh environments. The Altimeter Barometer III has a built-in sensitive air pressure sensor, which can measure the air pressure value of the location in real time, because the height is proportional to the location. Atmospheric pressure, can be used to measure relative altitude; when the altitude value is correct, the real-time altitude can also be measured. Barometer, altimeter, thermometer and compass four-in-one, no battery and charger required, no maintenance and repair, sturdy and reliable, because it does not require electricity, it is a very good and reliable outdoor tool. The altimeter of the barometer can predict temperature changes. Future weather is based on air pressure, so you can be prepared for the weather. Progress; easy to carry, reasonable design provides convenience. Bring convenience to your outdoor sports. This barometer is equivalent to having an altimeter, compass, thermometer. This barometer and altimeter is an environmentally friendly product with a purely mechanical structure, specially designed for you to do mountaineering, rock climbing, skiing and other outdoor sports air, it is a good partner for your outdoor activities and an important tool for your outdoor sports. Outdoor sports.