Bathing Suit Gretchen Is Wearing In Opening Of Show Where Did OC's Gretchen Get Her Bathing Suit?

Where did OC's Gretchen get her bathing suit? - bathing suit gretchen is wearing in opening of show

Gretchen wearing this bathing suit for the last two seasons, is a gray suit, navy blue bathing topless. It also showed that in the introduction. Where was it done? What brand is it?