I had 2 of these, and I donated them back to one of Soma's bra drives before I wrote down any impressions; so this is mainly from memory (but the measurements I provided were taken while I still had the bra in my possession). I love the fabrics used on the bras from Vanishing Back collection. I know blending nylon and spandex isn't an original recipe, but there's something about this collection that just feels extra fabulous. The fabric is also stretchy, so it's forgiving, but also, well, it stretches and with only one setting of the front-close style its lifespan is shortened. The design really does significantly reduce the appearance of lines visible under clothing in the back, but in order to achieve this, there is an awful lot of material in the back; but, again, because of the fabric, the excess never feels hot or constrictive.
I have a lot of issues with this bra but most of them are due just to being the wrong size. This does make a good t shirt bra, nothing ever shows underneath, HOWEVER the little rectangular metal thingys on the straps are the absolute worse. If the straps are supporting anything at all they will slide, poke you, and in the process lengthen the straps lessening support and become visible there. Beware those of large bust.