The boatswains call or pipe is often called the Bosuns Whistle was used to pass commands to the crew when the voice could not be heard over the sounds of the sea. Because of its high pitch, it could be heard over the activities of the crew and bad weather. Never be ignored again with our Bosuns Nautical Whistle Brass Keychain. This keychain is 100% brass that comes stamped with an anchor on each side and a swivel brass chain with a screw lock carabineer. This makes a perfect gift for the mariner in your life.