Simply plug your PestContro 500 device into an unobstructed wall outlet in the room to be covered by ultrasonic sound power, Coverage in a room can be improved by bouncing the sound off reflecting objects such as walls mirrors cupboard doors appliances etc, Obtaining a ricochet pattern will increase effective coverage, It is important to note that ultrasound cannot transmit through walls and doors so you can keep the ultrasonic coverage within a room by closing doors or leave the doors open to potentially extend the protection outside the room where it is plugged in, There will be a stronger effect of ultrasound within the room where the unit is placed, Package of 3, SKU: KLT129