You crack the nickel in one of these in the late afternoon when the sun goes down and your hands are starting to go numb:

1. The obvious - as a hand warmer(instant heat pack).

2. Put under a canister stove base to keep the canister warm in cold conditions as you cook dinner.

3. At night, place it in your fleece underwear, right next to the femoral artery. It\'s bliss, I\'m telling you. Or, in your boot liners/socks to keep the feet warm at night.

Crack another one in the AM and reverse the process.

Take from internet. http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=34