From The 1940s—to 1950s, a super vintage "Bob Low" Sz S or 6 ( mannequin is a six, and it fits perfectly)Aqua Blue Sleeveless Linen Day Dress with Embroidered Lace Trimmed Collar. Pleated straight Skirt, 5 White Fashion Buttons. Metal zipper side underarm. It is near mint, but there is one tiny light spot on the back, as shown. 
Measurements when laid flat -
Pit to pit - 18"
Shoulder -17"
Sleeve -n/a
Length -47.5"
Waist -13"
Hip -17.5"
Length of belt - 29.5" 5 holes