The Rentokil Beacon Dual Action Mouse & Rat Repeller is a simple to use, electronic repeller to help deter mice and rats and maintain a pest free home. The unit emits ultrasound which provides an uncomfortable environment for rodents, which will look elsewhere; at the same time as the electromagnetic part of the unit can help deter rodents from wall cavities in one whole floor of the house. We advise using one per floor for best results. It can be used in any room in the home. Being poison-free, it provides a long lasting alternative to poison baits or traps. Full instructions are enclosed with the product.