What Our Gearhead(R) Experts Are Saying:"I've worn these fleece bottoms on cold mornings under shells and even slept in them on shoulder-season camping trips. They're super warm without feeling bulky, and the bamboo-merino blend is soft enough for all-day wear without itch or sweat buildup."When the temps dip and we need reliable warmth next to skin, the Heavyweight Antarctic Fleece Bottom becomes our go-to layer. Made with a cozy and functional blend of rayon derived from bamboo, merino wool, recycled polyester, and stretch, this fleece bottom delivers next-level softness while managing moisture and movement. It's warm enough for solo wear around camp and breathable enough to layer under shells on frigid days in the backcountry. Designed with a performance fit that hugs close without restricting, these bottoms move effortlessly whether we're setting up basecamp or bootpacking to a powder stash. With its premium feel and insulating power, this is a cold-season essential we wear as soon as the frost rolls in.