The DX610 Pest-A-Repel is the best way to get mice out of the walls. Though the sound can not go through solid objects like walls, there a many air gaps that allow the sound to to be heard in the walls such as outlets, around door jams and baseboards, heating and air conditioning vents.
To determine how many of the DX610 mice, rats, rodent repellers you need for your home or business, check out www.electronicpestcontrol.net/product/electronic-mouse-repeller/.