The Beacon FM89 Advanced Mouse & Rat Repeller is the best available rodent repeller from Rentokil. This device uses both ultrasonic and electromagnetic technology, emitting a high-frequency sound and transmitting an electromagnetic field through the electrical cables of a building to drive rats and mice from nests within cavity walls, under floors and in roof spaces, where the majority of rodent problems are found.
One repeller can cover up to 232 square metres (2,500 sq ft), although it is recommended to purchase one unit per floor, i.e. upstairs and downstairs. It does not have any adverse effect on wiring or electric appliances. The repeller is perfectly safe for use around children, cats and dogs, but should not be used in a location with other rodent pets such as rabbits, guinea pigs or hamsters.