Fenix EO-1 and Bison, medium size tubular whistle. Just be safe and superglue the plastic insert, in place, in the whistle. Great,compact and inexpensive combination. It has worked for me for many years. Sneak a UtiliKey and a P-38 onto the keychain and you have a pretty good EDC set-up. The Bison whistle is loud enough for any purpose short of operating around helicpoters or other super loud machinery.