The PTS-2 comes with all the same features of the PTS-1 except the shock sensor, plus these new additions. The PTS-2 uses accelerometer technology instead of using a shock sensor as the PTS-1. The PTS-2 has an additional feature by using an interior keypad or key switch to arm and disarm the system. The keypad is user friendly and easily programmed. The PTS-2 is also equipped with a low battery alert system. The optional paging package (PTS-1P & PTS-2P) includes the pager base unit, pager and manual paging button to help notify you when you are away from the trailer.