I was wondering if any of you were familiar with the heating pads that Primus used to make for their canister stoves. They were clear things that looked kinda like a breast implant with some sort of liquid and a metalic disk inside. When you flexed the disk inside the pouch there was some sort of chemical reaction and the liquid would crystalize as it got fairly hot. I can only guess that these were intended to be placed under the gas canister to make it work in very cold weather, but I used to carry one inside my storm coat for emergencies. I kept it in one of those flat plastic containers that electrical tape comes in to avoid accidentally activating it while hiking. In really extreme weather I would flex the disk and drop it in my left shirt pocket, thus creating a nice warm thing inside my coat for the next four hours or so. They could be "re-liquidfy-ed" by boiling them for about 10-15 minutes....a rather wasteful use of fuel, but nice to have in an emergency. I used mine for a few years before it finally gave out and now I can't find them anywhere. They used to be about $4.50 and I gave a few of them as stocking-stuffers to my hiking buddies at Christmas.