The Harmonizer Ultra is designed for the most powerful emitters of EMF radiation in your life - those that broadcast over a wide area or that emit a large amount of EMF's. The Harmonizer+ is designed specifically for cell phones, which are also powerful emitters of EMF's but not as strong as those for which the Ultra is designed. The Harmonizer is for less powerful emitters of EMF's that communicate using WiFi or Bluetooth but are not broadcasting signals over a wide area - this includes wireless devices like laptops, tablets, computers, monitors, "smart" appliances, wireless speakers, etc.