Oh a whistle is a good idea. I didn't think of that. I figured I'd polish the tin and use that to signal in a worst case senerio. I don't know who effective it would be. I think a mirror is a good idea in an urban setting since it could be used to signal firemen etc... in a tall building to let them now that people are stranded in higher floors. Whereas a whistle, still needed my not be heard over whaling sirens etc. Thanks for the input. I think I need to add both. Any recommendations?