I'm off topic again, but I don't want to start another whistle thread just yet...

I was curious about the deeper tone whistles because they consistently do better on carry distance. I just got an Acme 559. It's noticeably bigger and deeper toned than the Acme 560. However, the tone on the 559 is too deep for my taste. I'm satisfied that the Acme 560 is the sweet spot for pitch for me.

I also ordered the Acme 649 Survival Whistle. It fascinated me that the this whistle was the only whistle heard at 3/4 mile by a guy wearing a hearing aid. It even beat out the Storm for that guy.

http://bigpigblog.com/category/signalling-2/