The Victor PestChaser Pro Rodent Repeller emits ultrasonic frequencies that send mice and rats scurrying. The device uses varying frequencies to prevent rodents from getting used to the noise and to keep them from returning. With more than 2 times the power output of standard ultrasonic pest control units this PestChaser is ideal for use in large rooms such as attics basements garages and warehouses. The 6 ft power cord allows for flexible placement. The device uses varying frequencies to prevent rodents from getting used to the noise and to keep them from returning. Once plugged in a red LED light lets you know the unit is working. While the Victor PestChaser Pro Rodent Repeller is unpleasant to rodents its high-frequency sound is safe for use around people and non-rodent pets when used as directed. Note: Ultrasonic sound cannot penetrate furniture cabinets or walls. Multiple units required for multiple rooms. Rodents that are hungry or tempted by easily accessible food may find another route around your protected area so it is best to remove all likely food sources prior to use. PestChaser works best to repel rodent populations when used with other rodent control methods as part of an integrated approach to trap repel and monitor infestations.