Solid brass ACME Clicker with high quality spring steel. Loud and reliable. Used by airborne troops on D-day landings and still made with the original tooling and presses.
 
The original cricket noise maker was a child’s toy made by ACME Whistle Company in England. But for D-Day, paratroopers were issued much more serious brass versions. With soldiers scattered willy-nilly behind enemy lines, the troops needed some type of stealth audio signal to identify each other in the dark of night.