The M-Flatiron 185 1/4 Zip Base Layer Top is as solid and reliable as its namesake rock formation in Boulder. Engineered for thermal versatility, Nuyarn technology offers supreme warmth and moisture management capabilities and unwavering durability that can\'t be beaten, even at heavier weights. FeaturesSuperior, bluesign® approved 185 g/㎡ Nuyarn merino technology offers unmatched warmth-to-weight ratio, 5x faster drying and remarkable durabilitySuperfine, mulesing-free, Australian merino wool for maximum softness and comfortIncredibly stretchy and elasticEasy Fit offers a modern fit with full coverageTargeted placement of eyelets for increased breathabilityChafe-free flatlock seamsGusset in the armpitsMachine washableLoop for dryingYKK zipper