Collections Etc Bell + Howell Ultrasonic Pest Repeller - 4pk, White Rid your home of mice, ants, roaches, spiders and other unwanted pests safely and easily without dangerous traps and chemicals. Uses inaudible ultrasonic signals to drive pests away. Simply plug a pest repeller into an outlet in each room that you want to protect. Plastic. Set of 4. Each measures 3"H.