This Real Time CDMA unit is distinctive from other Real time tracking system, 1st is its Very small fits in the palm of your hand easy to conceal on your person or in a vehicle the unit does not need to see the sky to work 2nd is that it works in location were other trackers wont like inside buildings or parking garages. How does it do this? By using Cellular assist. Plans start as low as $24.95What is Cellular Assist: when GPS Signals from any of the 24+ satellites cant be found the unit asks for assistance from cellular signals using GPS Triangulation mode. In this mode the unit determines its position through triangulation of the cellular towers.How small is it: it fits in the palm of your hand 3.1H x 1.8 W x .8 D weighs only 2.66ozWho would use it: executive protection, true asset tracking, child locates, vehicle tracking.See Specification sheet for rate plansAvailable accessories:ITEM # E1050- Waterproof case with magnetic mount