For each of the three companies, this report presents information on the company profile, central system equipment, software capabilities, the home monitor/receiver unit (HMRU), the transmitter unit, and the drive-by unit. All three companies offer a continuously signalling system which consists of a host computer, home monitor/receiver unit, and a transmitter worn by the offender. At this time, Digital client capacity is 500 with plans to upgrade equipment in the near future to allow for up to 5,000 clients. The Guardian system relies on network technology and thus will support very large data bases through multiple file servers. The TrakTek system, which will accommodate 300 to 2,000 clients, can be networked with an unlimited number of terminals and is compatible with laptop computers. 6 tables