At 70, and being a svelte little feller, I don't pack on much natural insulation so I depend on layering and hand warmers more and more in the colder weather. Though I buy the Hot Hands a case at a time I still find that the cost adds up after a while. The other day I had a brainstorm and tried putting the partially used (3 hours on an 18 hour rated warmer) into a small, tight seal sandwhich bag to see if I could stop the "fire" process by cutting off the oxygen. Well it does and so far I've used the same handwarmer pack for 2 mornings and an evening hunt and it still is good to go again. By taking away the oxygen supply the warmer packet stays soft and usable, they get hard when they are used up (just the opposite of some other things in life). So there's my 2018 handy deer hunting tip.