Vintage 70s Sears red blue plaid ruffle blouse

Vintage 1970s Sears red and blue plaid ruffle button down long sleeve blouse. Very lightweight, believe to be a poly blend. One button missing on one sleeve. No size tag. Closest modern measurement is a medium. flat measurements are approximate Pit to pit 20 inches shoulder to hem 24 inches shoulder seam to wrist 24 1/2 inches