"Awesome, no more mice, better than the 600/year pest guy for 4 years that didn't work, better than poison that they just keep coming back, awesome...needed two to cover the basement entries, working great for 3 winter months so far, doesn't bother cat or dog."Pest Deterrent Plug In Hanging The sounds are believed to even be capable of causing death by cerebral hemorrhaging if the animal is unable to get away, so the repellers might not be as humane as you might hope. Ultrasonic Ultrasonic devices operate through emitting short wavelength, high frequency sound waves that pest deterrent plug in hanging are too high in pitch to be heard by the human ear (generally accepted to be frequencies greater than 20,000 Hz). Humans are usually unable to hear sounds higher than 20 kHz due to physiological limitations of the cochlea, though there is considerable variation between individuals, especially at such high frequencies. Forsous Pest Reject The Forsous Pest Reject has proven itself particularly effective in driving away winged vermin, such as flies and mosquitoes, making it a good choice for use in areas where those flying insects swarm. sonny Says: May 29th, 2017 at 8:39 am WE BOUGHT FOUR OF THESE UNITS AND AFTER 30 DAYS THERE WAS AN INCREASE NOT REDUCTION IN THE RATS, MY UNCLE HAS OVER 30 BITE MARKS FROM RATS IN HIS LOW-INCOME APART AND APART MANGER REFUSES TO HELP AND HEALTH DEPT CANT DO ANYTHING, WAITING ON PERMISSION FROM POLICE TO ASK SOMEBODY IN NASHVILLE FOR HELP BUT that pest deterrent plug in hanging COULD TAKE MONTHS,MY UNCLE IS 68 AND SICK NEED TO GET THIS RAT PROBLEM SOLVED, THANK YOU Lola Says: April 13th, 2017 at 9:26 am These devices don’t work ….insects cannot detect the signal and rats get used to it in days.