The Iron Heart Whipcord N1 Deck Jacket may take its origins from the 1940's Navy version, but this one is clearly all Iron Heart. The backbone of the jacket is the tough-as-nails whipcord, which features hard-twisted yarns with a diagonal cord that make the jacket highly weather resistant. The interior has an alpaca/wool mix lining and even the pockets are lined with alpaca. All the historical details of the N1 jacket are here, but updated and improved upon by Iron Heart engineering. For this season, Iron Heart has added additional interlining for enhanced wind resistance.