I've had and used a Jon-e handwarmer for some time, off and on since I was about 12 or so actually. Today I bought a Zippo warmer so I can have one in each hand pocket of a jacket as well as just for comparison. So I thought I'd share my impression of each with you all here. They both work on the same catalytic principle, consume the same fuel and produce a similar amount of heat (and odor) so there's no clear winner in these categories. Not even a preference, it's just what they do and how they do it. The Zippo is slightly taller and wider where the Jon-e is a tad thicker and less tapered toward the edges than the Zippo. If one were to do the measuring and calculating, I'd guess they are almost identical in overall volume but I'm going to award a point to Zippo for it's rounded corners and edges. The Jon-e however, has a flat bottom allowing it to stand up on it's own. Point to Jon-e for tailstanding. The Jon-e comes in a nickel, or is it chrome?, finish and as far as I know, that's all that ever has been. Zippo sells both chrome and Black finish, I opted for the black for no particular reason. Point to Zippo for simply giving us an option. Did someone say Cerakote? Both come with a fuel measuring device so you don't overfill it. I generally don't use these as I don't spend all day outside. I just put a good squirt of fuel in and it lasts as long as I need it to. The Jon-e has a simple cup with a fill line whereas Zippo's is designed to dribble fuel in via a spout that looks like it belongs under Barbie's sink. Jon-e's cup also fits in the cloth bag with the heating unit nested inside. Zippo has a half fill line in case you don't know how to fill it halfway without a line. Capacity is nearly identical. Point to Jon-e for nesting cup storage. Once filled, you install the catalyst and light. With the Zippo, you simply get out your other Zippo (or any flame source) and hold the catalyst in the flame for several seconds. The Jon-e has a wick of it's own next to the catalyst and so needs only a spark or momentary flame, whereupon the wick lights and provides it's own flame for as long as needed. This flame must then be extinguished either by blowing or simply snuff it out with the lid. Suggestion to the manufacturer: add a sparker! Until that happens, no points, just differences. Then the lid slides on over the burning catalyst, okay it's not actually burning but catalyzing or undergoing a flameless exothermic oxidation reaction, whatever. The lid is mainly to protect the cat head and absorb and distribute the heat, it's full of holes for air circulation. The Jon-e lid slides on rather like assembling a just filled Zippo, smooth and snug but not too tight. Though you do have to worry about the wick getting in the way. The Zippo lid fits like a cheap Chinese knockoff, barely holding on, tight or loose in spots. Perhaps it's just my luck with this particular example. It holds together well enough to get it into the bag and once there it doesn't really matter, but I wouldn't trust this thing in my pocket without the bag. Point to Jon-e. After you have it lit and the lid installed, you then put the unit in a cloth bag that comes with and fits just right. The bag is an integral part of the system here. You control the heat by moderating the air circulation and thereby the oxygen supply to the catalyst, you control the air by fiddling with the bag. Want more heat? Open the top of the bag a bit. The bags are different but I don't know if I prefer one over the other. Both have their ups and downs. Jon-e has a red felt bag with gold cords that pull from either side. I've always liked this method of closing for such a bag as you just pull on the cords, but it's not very secure especially if you're trying to let it breathe by leaving it open a bit. Zippo came with a dark green velour bag with a single string and stop bead. It seems effective but not yet enough experience with it to say whether it works in the field. Maybe the perfect bag would have two cords with stop beads. Points for both. So unless my counting toes have failed me, that's four points for Jon-e and three for Zippo. Still, the differences are small. The fact is that in the real world, these are essentially the same and they both are well designed, last a long time on little fuel and just plain work. Either one can be a great comfort in cool weather or save your or a loved one's life in more frigid conditions.