Backless Long Mermaid Prom Dress: PromGirl ExclusiveHere's a backless mermaid prom dress that's perfect for grand entrances and showy exits. From the front, a plunging v neckline features and adjustable tie for support and style in this long prom dress. Additional adjustable ties accent the shoulders and frame the completely open back on this v neck prom dress. A side slit makes it easy to move and dance in this tight prom dress, and in back, ruching conceals the zipper and visually enhances the curves