Thanks a lot, Taurus! Experience like this in the tough environment is always valuable. Now I know what to take with me to freezing areas.

I have found history of the JetScream Whistle which is not presented on Ultimate Survival website. http://www.vtarmynavy.com/jet-scream-whistle.htm .
I think I will purchase ACR and later JetScream and then decide which will be carried every day.