I thought this was a great idea by Maidenform until I tried one.  I was really disappointed.  I wear a 38C and according to their chart I should be able to wear a Large.  It was extremely uncomfortable the first time I tried it on.  It was definitely TOO tight across the back.  I kinda felt like the person in the picture looks on their page specific to the underwire “adjusts-to-me”.  I have always had success with this brand, just not crazy about this specific product.  It put me in mind of the ads that say “one size fits most”.  I may be the exception, but just wanted to state my experience.