I bought these for my husband 2 sizes larger than his normal size. He has a large culo on his otherwise ectomorphic frame. The low V back doesn't really conceal any of it (other than making it legal to wear on the beach) as he juts out completely above the swimsuit in the rear. It's amazingly beautiful and I can't wait from him to wear it to the beach ! Highly reccomended !
This one fits differently. To get the back V high enough to stay in place, the front becomes very, very low and exposes some shaft - which may a feature, rather than a bug, depending upon how you look at things.