Eight Innovation EBD2766 Eight Build Complete Construction Kit to Create Your Own Fully Functioning Bat Detector, One Size, forAssemble this high quality ultrasonic detector and hear sounds normally beyond human ears! Listen to the sound of bats as well as other things that emit ultrasound. Youll be surprised to discover the number of usually inaudible sounds that surround us every day! This is an easy build kit all components just clip or screw together. Complete with clear, step by step instructions and cardboard case.