I have to admit, I was a little afraid to order underwear from the internet, that I had never seen or touched before to determine the quality or potential fit.  I was even more skeptical when it was advertised as a 1 size fits all.  Thankfully, I have been pleasantly surprised.  These are really nice, fit well, and are amazingly comfortable.  Imagine a glove that fits perfectly to every crease and bend of your fingers, like a surgical glove, just softer.  That's how these fit.  Out of the package, I looked at these and thought "how the heck is my big back side going into this little thing, but it fit just fine.  The fabric is one of those really soft, stretch fabrics that, well, stretch... and it allows them to fit really well.  I know these won't be for everyone, and since I'm getting older and have a midsection that's a bit on the round side now vs the flatter stomach of my youth, the top does roll down over the day.  With some underwear, that gets really uncomfortable because it causes that edge to dig in to your skin.  With these, that doesn't happen.  All in all, for the price, it's worth a shot if you aren't sure.  They are half the price or less of good underwear you would get from a local store, so it's well worth the money to try them out.  I liked them enough, I ended up ordering more of them.