CheXperiment: Bat detector with Checker Tobi - Hear what you've never heard! Discover the mysterious world of bats with Checker Tobi! With the CheXperiment bat detector, you can build your own device to make the invisible ultrasonic calls of the nocturnal hunters audible. The exciting kit teaches children the technical basics and makes them want to explore nature. Simply assemble it, switch it on - and your expedition into the night can begin! Highlights