The Trifield EMF meter is a true standard in our industry. It is considered by most to be the backbone in any dedicated investigators tool kit. Its ability to read fields includingelectromagnetic, magnetic and radio frequency makes it an essential tool for finding out if your activity is paranormal or man-made. This unit is also specially modified to include an audible alarm when it senses a field increase. Can make working in a darkened environment or with multiple devices easier. The Trifield makes a great meter to train a camera on also because it seems easier to watch the needle jump than LCDs counting up. Faster response too. Of course EMF readouts are important but, more and more attention is being paid to the RF's role in investigations and this is the perfect tool to explore them with. The unit is expensive yes, but essential if you are serious about your hunts