The Alpha Communications® IK543/XS series intercom kits feature our most popular apartment house intercom systems and configurations, for buildings with 2 through 8 apartments, at a price that can't be beat! The 'x' in the model number indicates the kit size (1-8 apartments). Each kit contains 1- IS204 (white) 'Universal' 4-wire indoor remote station (for each apartment), 1- IA543 intercom amplifier (with built-in electronic tone signal), 1- SS105B U.L. listed 16VAC plug-in transformer, 1- S1 Scrulox (Roberts head) screwdriver, 1- 'ES0' or ES612 series surface mount entry door station/panel (with 1-8 push-buttons) and coil of 2PRJ, 3PRJ or 4PRJ or 12WJ intercom cable (footage and type depends upon kit model selected).