What Our Gearhead(R) Experts Are Saying:"I wear the Intraknit Thermal Max 1/4-Zip for long ski tours and winter trail runs-it fits close like a second skin, breathes exceptionally well, and never feels bulky. The mapped insulation and mesh zones really do their job, and the merino regulates heat and odor better than anything else I've tried."When the conditions call for warmth without the weight, we layer up with the Intraknit Thermal Max Merino 1/4-Zip Baselayer. Built entirely from merino wool and mapped for activity, this next-gen baselayer keeps us dry and comfortable through cold-weather climbs, dawn patrol laps, and winter runs. Smartwool's Intraknit(TM) technology seamlessly integrates insulation, ventilation, and articulation for unrestricted movement and total performance. With mapped mesh panels to prevent overheating and terry loops for insulation where it counts, it balances warmth and breathability like few other base layers can. A quarter-length front zip and slim fit complete this performance essential, perfect for pushing our limits in winter's chill.