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)