MouseBlocker 2 Pack - 12V Under Hood Mouse and rodent deterrents 12V Powered: Simple 2 wire installation directly to your vehicles battery. No need to check flashlight batteries to see if they are dead or corroded. Trust your vehicles battery to constantly provide power to the unit and never leaving you vulnerable to rodents. Protects: Cars, Trucks, Motorcycles, RV's and tractors or anywhere there is 12V power available Trusted by 100's of NEW Car Dealers, Tractor Dealers and Repair Centers across North America Powerful: This specific ultrasonic frequency was chosen because it sounds like a Jack Hammer to rodents. When the unit is placed in the engine area it effectively makes the area uncomfortable for the rodents to nest therefor deterring them from chewing on costly wiring harnesses, fuel lines, hoses and computers. Convenient 2-Pack Ships Fast and Free!!