Price reduced again, was $95 Ultrasonic Bat detector/listener This detector can be used to listen to a variety of sounds produced beyond the range of human hearing. ie.: Bats, some insects, animals, air leaks(tires, air mattresses, air lines) power line arcing, are just a few of the high freq. sounds it will detect. This is a Heterodyne type detector. It is fine tunable, making it easy to adjust for different frequencies of interest. The supplied sensor has a peak response at 40Khz. Features: Speaker, earphones, or both.(earphones not included) Adaptor jack for 9 volt dc input (adaptor not included). Ultrasonic transducer (40Khz.) 10 turn fine tuning (frequency adjust) ON/OFF volume control. 9 battery included. To see other Electronic stuff I have, type "RSELECTRON" in the search box above.