This coat is only lightly insulated with low value polyester.  I bought it expecting an extreme cold weather parka but it's just a regular, low-cost parka.  I'm happy with all the design aspects which were goverment specified, and Alpha does a decent job of making it.  The nylon zipper is troublesome to get together and zip up sometimes which is bad for a piece of techinical gear.

I'm a men's size 36R and ordered size Small.  It fits fine but the hood is a little tight to wear a hat inside.  If I were to keep this, I might need a medium so I could wear a lot more insulation underneath it.

The main complaint is that the parka is not warm.  I need a warm parka to walk the dog in the winter and for field astronomy.  I walked the dog yesterday with the parka over my plain office clothes.  It was at least 25F and while I was walking there was no surplus of warmth.  Had I stopped, I would have gotten cold.  For astronomy, I wore long underwear, trousers, two shirts, a fleece, ski gloves and -60 rated boots.  I had a watch cap but also tried the hood.  It was at least 15F and for 30 minutes the parka was fine, but by the second half hour, I was freezing cold.

Astronomy is a tough test because you're just sitting still.  This parka would have been warm if I was snowshoeing or skiing, maybe too warm.  But without additional insulation it was inadaquate even for walking the dog in the sun, and the conditions above 0F were hardly extreme.

I compared this parka to my Carhart cotton duck parka that is also lined with polyester.  They're about the same except the N3-B has a much more thorough neck closure and snorkel hood -- otherwise it's not much wamer.  The Carhart is cotton duck canvas which is much more abrasion and burn resistant than nylon.  With a scarf to close the neck, it seems equivalent to this N3-B except the hood.  I don't have the optional carhart hood to compare.  The Carhart is less than a hundred dollars on Amazon.

Since neither is adaquate for extreme cold weather without a lot of down or wool insulation underneath, I will probably have to look at Canada Goose or something.