This product integrates an altimeter, barometer, thermometer, and compass. It is made of high-quality materials resistant to tears, impacts, pressure, cold, and heat, making it suitable for various harsh environments.The altimeter and barometer feature a built-in sensitive air pressure sensor that measures the real-time air pressure at your location. Since altitude is related to atmospheric pressure, it can be used to measure relative altitude. After calibration, it can also provide real-time altitude readings.Combining a barometer, altimeter, thermometer, and compass in one device, it requires no battery or charger, eliminating the need for power maintenance or repairs. Its robust and reliable mechanical design ensures functionality without electricity, making it an ideal outdoor tool.The barometer and altimeter can help predict weather changes based on atmospheric pressure trends, allowing you to prepare in advance. Its compact size and practical design make it convenient to carry and use during outdoor activities.This barometer and altimeter is an eco-friendly product with a pure mechanical structure, specially designed for outdoor sports such as mountaineering, climbing, and skiing. It serves as a reliable companion for outdoor adventures and is an essential tool for outdoor enthusiasts.