Spot Satellite Messenger Satellite messenger with GPS tracking for keeping users safe on adventure trips.Purchasing a service plan is required in addition to purchasing the SPOT unit. SpotChecking feature alerts friends and family of your precise location SpotCasting function lets friends and family follow your progress in real time Sends GPS coordinates and distress message to Emergency Response Center Satellite technology works around the world; measures 2.75 x 4.38 x 1.5 inches (W x H x D)