34 34 Square Neck Long Sequin Formal Dress 657 Facebook [] Facebook. Set the tone for glamour when you slip into this long sequin formal dress that is as jaw dropping as it is sparkly. The fabulous long sequin dress is fully sequined from the square neckline to the floor, while thin shoulder straps attach to the horizontal band that flows over the open back. The gorgeous open back evening gown smooths over the hips and flows to a dramatic floor length before ending in a small train. Offered in misses and some extended sizes, this long sequin formal dress is richly designed for the girl who loves a bold look for prom, galas, and other formal events.