They're available from places like Comet, etc. No cleaning fluid required, you use one cloth wet and the other one dry.
I was really cynical when I first saw them, (came free with stainless steel cooker, which they're really good for) because one looks like a flannel and one likes like those cloths you get for cleaning glasses, but way bigger. Apparently it's something to do with the texture. They say when you wash them not to use any fabric softener, so that's a big giveaway.
Take it from a smoker - they are brilliant. You can even use them on bodywork after cleaning to stop water marks.