This beautiful has the ILGWU tag (very faded) with the (R) symbol (dating it to after 1964).  The material tags are missing, but it definitely feels like a polyester blend (or acetate depending on the year).  She is a beautiful pastel rainbow plaid! The front buttons are functional, but because the fabric has stretch they do not gap open.  The waist band still has some stretch, but not 100%.  Belt loops are intact, but I do not have the original belt.  This dress will come with the purple ribbon (NOT the leather belt).  There are many options for styling this beautiful!

Oh, and the best feature... she has POCKETS :)  She is unlined and slightly sheer.

 As far as vintage sizing, she is a vintage size 10...my dress model is a modern size 6/8 and this dress fits her well with some room.

Measurements (inches) are shown in the last photo; taken with item flat, buttoned/zipped, and unstretched.  Double when a circumference is needed.  Please use as an approximation, and compare to a garment you know fits you well or your own measurements.  "Hips" are measured half-way between the button/zipper, and the crotch seam used to measure rise and inseam; "thigh" is measured two inches below this seam.