2. Ultrasonic sound waves do not penetrate walls, floors or the ceiling!
The physical properties of ultrasound make it impossible for the frail sound waves to even penetrate a wall paper. The waves reflect on hard surfaces like light in a mirror.Therefore, don´t get the misconception that a single device installed in a room will get rid of your mice in the walls, in the attic or in the crawling space underneath the house.
To completely get rid of rodents in your house (that´s what you want isn´t it?);
1) the pest control appliance(s) must be installed in the "landing" space(s) of the rodents, like the attic and/or the crawling space underneath, (thirsty mice will pass through their landing around the clock, in order to get some water, dew or snow outside the house....!)
2) the device(s) must be powerful enough and preferably equipped with water resistant speaker system for many years of peak performance in cold, damp spaces.
Moral: Don´t be penny-wise and pound-foolish! Whatever prime features a $29,95 device is said to have, e.g. electromagnetic powers, don´t think for a moment it will rid pest in your entire house. It would just be wishful thinking on your part. Now, let´s have a look what we have to offer.....