Vintage 90s Polo by Ralph Lauren Sweater Vest Blue Single Striped. 100% Cotton. Masculine size medium. Blue knit sweater vest with white single stripe. Logo on the front. 

Item has been laundered but does have a couple of spots on the back, as shown. 

Measurements with the garment laying flat:

Pit to pit: about 21.5 inches 

Length: about 27 inches