The ACME Thunderer is the highest grade metal whistle offered by ACME. It is a heavy nickel plated brass whistle with cork ball in the whistle chamber and has a lanyard ring already attached. The whistle is the standard size measuring in at a 1/2, 1-7/8". The whistle in known for its thundering super loud clear tone when blown. This is the official whistle used in NCAA & NBA tournaments, therefore you know that you are receiving the highest grade metal whistle on the market. Make sure to check out all of CSI Cannon Sports' team colored lanyards to attach to any whistle of key chain.