The Tracker 2720 & 2730 are modems that feature a secure encrypted challenge/response mechanism. The Tracker 2740 series can be used as an intelligent application platform but has fixed levels of connectivity. The Tracker 2750 is for those customers that need the ability to swap and change the configuration of the Tracker in the field. We are also able to develop additional modules for the Tracker 2750 if you have more specialized requirements.