Tested. Works fantastic!
Ordered 4 and did the job for a 3 bdrm house. I put 1 each on the tv receptacle, computer, treadmill and in the center of the house. Readings thru the house are about 27 but I may need 2 more, the treadmill needs 1 more but only when its running and a second tv needs one but its rarely used. Note that if the tv is on then all outlets i  the house and unattached garage go to about 700!  There are 4 kinds of emf's and you must test with the proper tool, dont let anyone fool you. There is Rf (microwave ovens, cell phones and towers,  roku with non infared remotes, xbox, smart meters and cordless phones, baby monitors) the other 3 are dirty electricity, magnetic fields and electrical fields.
Rating: 5 stars