Vintage Mod 60s-esk Mini Dress

In great condition colorful vintage mod like mini shift dress (maybe from the 80s?). Not super form fitting, though it is pretty short (I’m 5’.6”). There’s a small zipper in the back at the neck. Not much stretch to it overall. I would usually wear with tights and boots in the winter. Measurements Tag says M, but it feels more like a S 15” at the middle (there’s not much of a waist) 29” from shoulder to hem