Don’t let the naysayers get you down. I have a variety of stoves for survial use and I bought up 10 of these last year for $1.00 each at Dollar Tree.
Used a couple of them to make bacon and eggs and a few other meals to test them out. Yes, as some others say there are better (often more costly) solutions, but I find these easy to use and self contained. You can refill with denatured alchol. Don’t use regular rubbibg alchol.
Explore some of the other suggestions by some of the others if you are making a survival or emergency prep. Having more than one solution is always a good idea.
Denatured alcohol is the best. Take a cat food can and poke small holes around the top with an ice pick. Make a stand for your pot out of wire mesh and use tinfoil as a windscreen. One oz of DA will boil two cups of water. Use a small cough syrup measuring cup to measure the DA. It’s cheaper and burns hotter and more consistant than the gel. Only put in the amount of DA you need and just let it burn dry.