The SPOT Satellite GPS Messenger provides a vital line of communication with friends and family when you want it, and emergency assistance when you need it. Using 100% satellite technology, SPOT works virtually anywhere in the world, even where cell phones don’t – all with the push of a button. SPECS Height: 3.7" (9.4 cm) Width: 2.6" (6.6 cm) Thickness: 1" (2.5 cm) Weight: 5.2 oz (147.4g) Operating Temp: -30C to 60C (-22F to 140F) Operating Altitude: -100m to +6,500m (-328ft to +21,320ft) Humidity Rated: MIL-STD-810F, Method 507.3, 95% to 100% cond. Vibration Rated: Per SAE J1455 Battery Type: 3 AAA Energizer™ Lithium Ultimate 8X SPOT Message Schedule: SPOT is designed to provide outstanding quality and reliability. With a perfect view of the entire sky, the SPOT Messenger is designed to transmit virtually every message. In everyday conditions, the view of the sky is often blocked due to hills, buildings, or other obstructions so it is normal for some messages to be blocked. That is why the SPOT Messenger automatically sends multiple messages in every mode, giving you excellent overall reliability. In some modes this means multiple attempts to send the same message, while in other modes it means regularly updating GPS coordinates and sending a new message. Placement of your SPOT unit can make a difference. Experiment with placement until you are familiar with the reliability of your operating environment.