I wear this around my hips under my shirt during hikes and runs and it's very comfortable and flat.  I can fit my ipod shuffle, ID, phone and car key in it easily.  Everyone that I exercise with asks me where I got it and ends up buying one.  I think there are some bad versions out there that are not as comfortable or discreet.  Who wants everyone knowing you're wearing a fanny pack!  This is not the 1980's version.