I was worried one size wouldn't work since I'm closer to a 46, but this fits perfectly without feeling tight. The side openings are actually placed well and the straight neckline sits right where it should.
The sheer black fabric feels surprisingly soft against the skin, not scratchy at all. I'm between a 42 and 44 and the one-size fit works fine on me, though the side openings sit a bit higher than I pictured.