I'm looking for flat whistles for an urban travel kit. They should be shrill enough to be heard over background noises, reconizable as a whistle, and do not require a lot of lung power. The hard flat surfaces and high background noise of the city requires a difference whistle then wilderness. I already have a Storm dedicated to off pavement duty.

My choices are
Acme 636 slimline tornado
ACR WW-3
Fox40 mini with vanes shaved off

Thoughts?
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