I don't think it is pure naphtha, at least not anymore. Don't ask why I know, but I looked into it a while back.I never liked the throwaways either. I have two Jon-e-Warmer versions of those Zippo heaters. I was sorry to see that they no longer make their own brand of fluid for them. I don't know what the formula was, but it didn't have the same odor as the Zippo which is naphtha based, if not pure naphtha. I still use them, but I have to wash whatever clothes they come in contact with when I get home.