This highly-effective Mini PestChaser 3-Pack produces high frequency ultrasound that repels rodents away. The Mini PestChaser is equipped with a new nightlight feature that provides a soft glow in the dark. The unit’s mini size and discreet design make it ideal for living areas. The ultrasound, with over 80 oscillations per second, emitted at varying volumes and varying frequencies keep rodents from adapting to the sound. The sound cannot by heard by humans or non-rodent pets such as cats, dogs, birds and fish. Most users experience a reduction in rodent activity in as little as 6 to 10 days. One unit typically provides 3 to 5 years of service.