 They come out on the market. I buy them. I want to see what they do. I want to see what I can learn from them. This one, I bought it. I used it once, and I've forgotten to actually use it because I brought it home. It's in my computer bag, and I'm sorry. I know nothing to say about this thing other than it measures carbon dioxide levels. And the claim, but I can't say anything if it's real yet. The claim is that they can measure your metabolic rate.