The F950-650 XP95A Smoke Detector is designed to be connected to a two-wire loop circuit carrying data and a 17V to 28V DC supply. The detector is connected to the incoming and outgoing supply via terminals L1 and L2 in the mounting base. A remote LED indicator may be connected between the +R and -R terminals. This detector is a direct replacement for the F900-650 Addressable Photoelectric Smoke Detector.