This vintage mackinaw was made in 1942 by the Jacob Siegel Co. for the US Army. It is shawl collared and double breasted, with flapped patch cargo pockets and epaulettes.
Chest (pit to pit): 21″ (doubled = 42″)
Shoulder to shoulder: 18″
Sleeve (shoulder to cuff): 23-1/2″
Length (base of collar to hem): 32″