Batbox Baton | Ultrasound Bat Detector

This was expensive, but it's very nice. I've used bat boxes before- those were the heterodyne variety which had to be tuned. This kind (frequency division) is much simpler to use. Both have advantages and disadvantages.This one seems more susceptible to noise (because you can't tune it away from the noise). So if you rustle it when holding you'll hear that amplified. If you have crickets or frogs too, that will come in louder than the bats. BUT, you don't miss the bats, either... when you have to tune you're pretty much guaranteed to miss a lot of what's out there.