Traking devices that are secured to an asset such as a boat, caravan, machinery etc. Asset trackers are normally connected to an external power supply (high capicity battery) but also usually contain their own internal battery that will last a few days if the main power source is lost. External antenna are often available for asset trackers. This allows the tracker to be placed in a dry location within the asset and the placement of the antenna to maximise the receipt of GPS and GSM signals.