Theory Daruba Register Plunging Back Boat Neck Slit Dress, Black, 4 A coyly pleated side--and plunging back--flaunt both your gams and your glam side in Theory's of-the-moment midi dress. Boat neck, sleeveless, cascading side ruffle, side slit. V-back, concealed back zip, lined. Viscose/acetate; lining: polyester. Dry clean. Imported. By Theory.