To determine which ModelMinder is needed for each model Apartment/Home you will need to know how many breakers carry the LIGHTS ONLY as well as how many stair cases (if any) are in the model. If your lights are carried on 1-6 breakers the MM-6K-WIRELESS is a large enough unit. If your lights are on 7-10 breakers you will need the larger MM-10K-WIRELESS unit. If there are stair cases in the unit (living area downstairs bedrooms upstairs, etc.) then you will need the unit with a motion sensor either the MM-6KM-WIRELESS or MM-10KM-WIRELESS. ALL MODELMINDERS COME WITH A WIRELESS DOOR SENSOR.