Saintland Automobile Mouse Pest Repellent-Cast aluminum case Repel rodent and pests away from your Automobile, to avoid power cords and liquid pipes to be bite off. Small size, can be installed in a small space. Easy install like 123, under hood. also can install in passenger cabin. Cast aluminum case avoid material aged by heat and temperature changing, ensure longest working life. Automatic control, when engine is running, SD-048 will be sleep, when car stop and park, it will start to work automaticlly. The frequencies of the ultrasonic waves are always changing in order to avoid mouse/rat to have any "adaptability" and "immunity". Maintainance free. give you a peace mind of your car from rodent biting. No poison, friendly for human and non rodent pets.