The Schott Pea Coat
The pea coat is a perennially popular winter coat. Its timeless double breasted design, original functionality of keeping navy men warm at sea, and wide availability across a number of different price points make it a go to in cold weather for men and women of all ages and styles.
Schott NYC's pea coats (Schott has, in the past, held the U.S. Navy contract) are an American classic, and are widely available on ebay, in army and navy surplus stores, at flea markets, and in thrift shops. I purchased mine on deep clearance for about $80 years ago at a brick and mortar shop in Ann Arbor, MI when I was a grad student. It kept me warm through many any icy and snowy Michigan winter. They retail now for a bit over $200, but are well worth the investment if you're looking for a warm American-made winter coat that will never go out of style, and you can easily find them priced pretty far under the MSRP.
They make a slim fit version too, but mine is the original cut, and I feel they run pretty true to size. I wear a pretty standard 40R off the rack, and my pea coat is a 40R, and fits a chunky sweater underneath quite comfortably. If I were buying one now I might try a 38, especially so if I thought I’d rarely need to layer anything heavy underneath.