Ultrasonic Leak Detector AC Frequency Response 35 to 45 KHz Range Centered At 40.5 KHz Function Quickly Pinpointe The Origin Of Ultrasonic Sound Produced By A Variety Of Sources Such As Refrigerent Leaks Electrical Arcing And Worn Bearing Includes Ultrasonic Detector Probe Extention Headphones 2 InD In Size Batteries Hard Plastic Carrying Case