Fantastic value. Each ultrasonic repeller plugs into any unobstructed wall socket, and emits a powerful ultrasonic noise which we can't hear, but which mice can't tolerate. Each unit covers a single room. For total protection, use along with one of our "Whole Home" pest repellers. This product should not be used in the same room as rodent pets, such as hamsters, gerbils, guinea pigs or rabbits, but it can be used near cats, dogs, fish, birds or reptiles, as these animals won't even know it is there. This amazing product uses barely any electricity, so you can leave it plugged in 24 hours a day, 7 days a week, all year round. It is completely chemical free, and unlike some budget pest repellers, it exceeds all CE safety standards. Protect your family the modern, clean, environmentally responsible way with PestClear and STOP electronic pest repellers.