This is what it says it is. If you are looking to focus heat (and, in theory, weight loss) on your chest, belly, and back ... then this does the job. I normally wear either a L or XL T-shirt, I ordered this in a 2XL ... I could not have gone any smaller and still be able to 1) put it on, and 2) expect to be able to breath with it on. I have noticed a definite difference since I started wearing this thing during my morning bike rides.