I won't spend a dime on it!!!! From what I've read and from what I understand about activated carbon there's no way that crap works.(Example) I'm a painter, guess what my mask filters are made out of, thats right activated carbon. The instructions say after 8 hours of use or just even out of the sealed bag there shot. Mabey I should just throw them in the drier for a while to reactivte the carbon....right? I don't think so!!! There are also alot of guys that swear by it. I can't explain it!