So sophisticated, this open-back long formal prom dress is simply elegant. From Dave & Johnny, this long designer dress defines femininity from the scoop neckline to the floor. With a sexy open back, this princess-cut evening gown gets a fitted look with criss-crossing bands that lace up before tying into a fully adjustable bow. Hip-skimming and sultry, this long formal dress flows to the floor before pooling into a dramatic train that follows behind. Offered in misses and extended sizes, this open-back long formal prom dress from Dave & Johnny is surprisingly priced under $300 for prom, galas, and other fancy formals.