http://www.ebay.com/itm/271870719570
This vintage mackinaw was made to 1942 specifications, and was probably made in 1943. The official term was, Overcoat, Wool, Doeskin O.D. Officers Short Style. This was a successor to the shawl collar overcoats issued from the 1920s-early 1940s. I have one of those in a separate listing. The coat is double breasted, with flapped cargo pockets and epaulettes. It is fully lined.

Tagged size: 36
Chest (pit to pit): 20″ (doubled = 40″)
Shoulder to shoulder: 18-1/2″
Sleeve (shoulder to cuff): 24-1/2″
Length (base of collar to hem): 31-1/2″