Black & Decker EX900-A-TP1 Ultrasonic Pest Repeller (XL Room) (Discontinued by Manufacturer)
Black & Decker Ultrasonic Pest Repeller have a 100% Duty Cycle which means the unit is continually emitting ultrasonic "noise". The frequency ranges from 26-74Khz at 105 decibels in a constant fluctuation so to continually disrupt the pests and force them from your home. Pests are repelled because they cannot adapt to the constantly changing array of complex ultrasonic and sonic sounds.