Rihanna and Brooklyn Decker posed pretty at the London photocall for their new movie Battleship. While it appears that the dresses they picked — Rihanna in Alexander Wang, Brooklyn in Stella McCartney — are vastly different, upon closer inspection, they share one sexy detail. Both frocks have exaggerated halter necklines that show off their beautiful shoulders. Notice how each cut caves into the center of their chests, revealing parts of their decolletage. It's a small detail, but one that can work major wonders. First, it can give the illusion of curves, plus it can also offer subtle sexiness, especially when the hemline of the dress is longer. Inspired by Rihanna and Brooklyn, we tracked down a handful of halter dresses with similar cuts, so shop your favorites below.