The classic N1 deck jacket was first produced for the US Navy in the early 1940s. Since then, copied a lot, it has become a true style icon piece. The Iron Heart version remains fairly faithful to the original jackets but with significant improvements in properties. A big, but unseen, change we made is an extra insert in the inner lining to increase wind resistance. The N-1 by Iron Heart is an absolute classic, goes perfectly with your 21 oz jeans and keeps you nice and warm. For this year's version, the insert on the collar has been added and the pocket placement has been slightly optimized.