Backless Long Beaded Formal Dress: Mac Duggal 5669 Pin on captions. Shine all night long in this open back long beaded formal dress 5669 by Mac Duggal. With swirling beads from the deep v neckline to the hem, this long beaded dance dress is a sparkly choice for prom, galas, and other formal events. The long beaded evening gown has supportive shoulder straps that lead to the strappy open back, while the long skirt hugs the hips before draping to the floor. Combining intriguing details and a flattering silhouette, this long beaded formal dress is a stand out style for your celebration.