Proudly attend your formal event in this long sequin prom dress that shimmers with every move. Fully-sequined from the plunging v-neckline to the hem, this open-back evening gown has scattered floral embellishments and thin shoulder straps that adjust for the best fit. From Amelia Couture, this long designer dress is a slinky style that hugs the curves before opening in a side slit and flowing to a dramatic floor length. Surprisingly affordable, under $150, this long sequin prom dress is a versatile choice for prom, military balls, and other formal events.