Sun Company AltiPort - Detachable Windshield and Dashboard Altimeter and Barometer | Altimeter for Cars and Trucks | Reads Altitude from 0 to 15,000 Feet EASILY MOUNTS TO DASHBOARD OR WINDSHIELD - AltiPort quickly mounts using levered suction cup and sticky pad. Easily remove altimeter from mount and take with you in your pocket or pack on the trail. ACCURATE READINGS - Adjustable dial lets you account for high or low pressure systems so that you get the most accurate reading possible. BATTERY-FREE - This analog altimeter is battery-free and simply adjusts based on the surrounding barometric pressure. EASY-TO-READ SCALE - Easily measure altitude up to 15,000 feet. Barometric pressure is measured in inches of Mercury (Hg). FULL INSTRUCTIONS INCLUDED - Easy step-by-step instructions help you learn how to set and adjust your SUN altimeter.