It might interest you to know what number of units are required for your house. It all depends on how large your home is. For small homes or flats measuring less than 1500 square toes, one tool will suffice. One tool is sufficient for massive homes (between 1500-3000 square ft). Two gadgets are required. https://marylandreporter.com/2022/03/31/miracle-watt-does-it-really-work/