The Jacket, Field, O.D. (also unofficially known as O.D. Cotton Field Jacket, Parsons Jacket, M1938or M1941) is a field jacket that was used by soldiers, most famously during the beginning of . In 1941 it started to be phased in as a replacement for the wool four-pocket service coat of , but around 1943 it was replaced in turn by the improved model.