It was -6 on the thermometer when I left the house on my snowmobile to go coyote hunting the other day, usually this is 8 hours straight of no heat and often times 45 mph on the sled for 10 minutes at a time, by noon it was maybe 10 degrees, I wear first lite merino wool base layers, I can’t remember the name but there super thin, microtex pants, under armor hoodie, with a filson wool vest, and sitka stratus jacket and bibs, if you wana find out if your stuff is windproof jump on a sled at 45 mph when it’s -6, Sitka stuff is real and for me worth the money, google like crazy and you can find deals, the difference with Sitka for me is before when I hunted in these extreme temps I would be so bundled up I couldn’t hardly swing my rifle, with Sitka I am still warm but have complete freedom of movement, there is just so much less bulk for the same amount of performance as other stuff, I sold off and gave away everything else I owned and made the switch and have zero regrets.