kidde Detector mounting base has wiring terminals that are accessible from the "room-side" after mounting the base to the electrical box. The bases mount to North American 1-gang boxes and to 3½ inch or 4 inch octagon boxes, 1½ inches (38 mm) deep. They also mount to European BESA and 1-gang boxes with 60.3 mm fixing centers. The KI-SB4, KI-RB4, and KI-IB4 mount to North American 4 inch sq. electrical boxes in addition to the above boxes. They include the GSA-TS4 Trim Skirt, which is used to cover the "mounting ears" on the base. The KI-ABST mounts to a 4 inch square box only. Kidde Detector Mounting Base Main Features Next generation optical smoke sensing technology Wide 0.53 to 3.94 %/ft. (1.7 to 12.35 %/m) smoke obscuration Uses Existing Wiring Automatic Device Mapping Up To 250 Total Addresses Per Loop Two Levels of Environmental Compensation Two Levels of Dirty Detector Warning Twenty Pre-Alarm Settings Five Sensitivity Settings Non-Volatile Memory Electronic Addressing Identification of Dirty or Defective Detectors Automatic Day/Night Sensitivity Adjustment Bicolor (Green/Red) Status Led Standard, Relay, Fault Isolator, and Audible Mounting Bases Sensor Markings Provide Easy Testing Identification compatible with: KIR-HCD Heat and CO Detector