I just wanted some people's opinions on those little hand warmer pouch things that're supposed to warm up when opened and shaken for a bit. I bought a box of them last year (I think they were 'lil hotties' from Costco). I cracked one open and shook it around at the house in SLC and it seemed to heat right up and work great. However...that weekend I was up around 9500 feet and it was quite cold, I take one out, open it up and shake it around for 5-10 minutes, not one bit of warmth. I figured it might have been a dud and tried 3 others, all the same. Is there something about these things that makes it so they won't work in very cold temps at high altitude or something? Seems to me that's the place they especially need to work....
