The Aiphone KB-3MRD audio/video master station works with the KB Series of door stations and sub-master stations (sold separately) to enable audio communication with visitors prior to authorizing access. The station connects to up to three door stations to monitor multiple entrances, and works with up to four sub-master stations to extend coverage to multiple rooms or large areas. The handset provides privacy when communicating with a visitor or between rooms. An incoming call activates the display on the 4" LCD color monitor to aid visitor identification, and picking up the slim handset opens up the line of communication with the door station. The video monitor controls allow vertical tilting of camera on the door station (sold separately) to customize the view of the entrance.Each connected door station has a unique two-, four-, or eight-tone chime with LED indicators to alert the master station operator to which door station is calling. The chime and audio volumes are adjustable. The door-release button works with an electric strike (sold separately) to remotely unlock the entrance for the visitor and, when used with two door stations and the Aiphone RY-3DL door-release adapter (sold separately), the master operator can select which connected door to release. The all-call button broadcasts to every sub-station connected to the system. The monitor button can be pressed at any time to listen and receive video feed from the door station. Internal calling is supported between KB master and sub-master stations. The housing is fire-retardant white ABS plastic.SpecificationsOverall dimensions195 x 185 x 84 mm/7-3/4 x 7-1/4 x 3-5/16 inches (H x W x D)*Maximum allowable distance (master to door station)330 feet using 22 AWG wire; 650 feet using 18 AWG wireMaximum allowable distance (master to sub-master station)165 feet using 22 AWG wire; 330 feet using 18 AWG wireMaximum allowable distance (master station to call extension speaker)165 feet using 22 AWG wire; 330 feet using 18 AWG wireCompatible wireAiphone 871802 (sold separately)Door-release contact rating12VAC at 400mA. Use Aiphone RY-24L relay module for larger contact rating.Power requirements24VDC. Requires Aiphone PS-2420UL power supply (sold separately).*H is height, the vertical distance from the lowest to highest point; W is width, the horizontal distance from left to right; D is depth, the horizontal distance from front to back. Door intercom systems allow an occupant of a building to communicate remotely with a visitor through at least one door intercom and master intercom. Master intercoms with a door-access button remotely unlock the door for the visitor.Aiphone manufactures intercom systems for residential, business, and healthcare structures. The company, founded in Japan in 1948, has its North American headquarters in Bellevue, WA. Aiphone meets International Organization for Standardization (ISO) standards 9001 and 14001.What"s in the Box?Aiphone KB-3MRD master station(2) options connectorsMounting hardwareInstructions