The so-called N-1 jacket and trousers of the same material were a set and adopted for the U.S. Navy ship crew between World War II and the Korean War.
The outer material is a cotton grosgrain commonly called “jungle cloth,” the same material as other deck jackets. The lining is alpaca mohair and wool pile with excellent windshield and insulation. The N-1 navy blue model was adopted in 1944, and the khaki model was distributed in the following year, 1945. The changes made were not limited to color. The two models have distinctive differences, including the later model’ s omission of the alpaca mohair sewn on the inside of the cuff, simplification of the loop attached to the underarm of the lining and hem drawstring, increased size of the hem drawstring eyelet, and relocation of the underarm eyelet.