There are a few items that we have used that have improved our hiking experience. The Hot Hands Hand Warmers are one of them. Not an essential, per se, but there are a few things that are totally worth packing in and packing out, because they just make everything better. The original HotHands warmers provide up to 10 hours of 130-140° F warmth in a soft 2″x 3″ pack. Air activated and environmentally safe, these warmers are a must for any outdoor trip. While safe for the environment, you don’t want to burn them or bury them. This is absolutely a pack in/pack out item. But if it’s seriously cold, you’ll be so glad you did.