What Our Gearhead® Experts Are Saying: "Merino 250 is my go-to when temps drop. It breathes on climbs, insulates on windy lifts, and never gets funky. The slim fit layers cleanly under a shell and those flatlock seams and smooth shoulders mean zero hot spots under a pack."We trust Smartwool’s Merino 250 Baselayer Crew when winter finally bites. The Merino 250 Baselayer Crew settles in as our first layer from dawn skintracks to frosty dog walks, and Smartwool’s soft 100% merino keeps us comfortable when the forecast can’t make up its mind. Naturally thermoregulating and odor-resistant, this midweight knit holds in heat without stifling on the uphill. Flatlock seams and smooth shoulder panels reduce friction beneath pack straps, while a slim, next-to-skin fit disappears under midlayers and shells for streamlined warmth on ski days, hikes, and cold commutes.