yes, I thought so as well when I bought in New York, tried it on at home in Fl. and as per the usual when I see stuff on me , I went eww, yuck , not on me, perhaps on someone else with a smaller waist line than I, it does fit a ex large , very well and then some. I put it in my closet and left it there, til now!
That would be my best guess considering how it form fits , it looks to be a size 12 , however it fit me, with lots of stretch to go and I am in a XL, as you can see from the shot of the back of it , there is elastic backing, and the straps adjust as well.