Listed is a vintage blue satin with black lace accents, coordinating blue bow, two fabric covered matching buttons, and sheer nylon black back panty. Appears to be a size small. Hi cut bikini style. 
Lying flat, 12" across unstretched, 16.5" stretched. Note that the front does not stretch.
Top to bottom 10".

Vintage good to fair condition. Elastic in back (there is none in the front by design) has good stretch and return. Very faint discoloration at gusset. Some picks in nylon. Size tag is missing, please be sure to see all photos and measurements. Thank you for looking!