Self contained device fits in the palm of your hand. No external antennae needed, just plug- & -play. Location information is reported using a direct GPRS data connection. Mapping for the entire world using the latest cutting edge 3D maps from Google and Microsoft. Built-In Enhanced GPS / GSM AntennaReal-time location reports every 15 seconds. Address / Location Data (accurate within 9 meters) 4-Hour Battery Charge TimeBattery Capacity 1100mAMotion-Activated (for battery conservation--in weatherproof case only) Geofence feature sends alert if the target moves from pre-defined area. GPS assist function using GSM network, boosting location sensitivity when GPS signal is temporarily lost. Durable, lightweight, water-resistant housing. Enhanced sensitivity for indoor and outdoor reporting. Tri-band GSM 850 / 1800 / 1900 MHz for worldwide coverage. Can be hooked up to 12 volt DC for permanent hardwire connectionMeasures 2. 5" (L) x 1. 78" (W) x 0. 9" (H) (65mm x 43mm x 23mm) Weighs 3 oz / 85 grams (without weatherproof enclosure)