Here's what other sites are saying:
The Nau M1 Rib Crew shirt is a high-performance, next-to-skin piece that combines the warmth and breathability of merino wool with a unique rib-knit for natural stretch, insulation and softness. Soft merino wool naturally manages next-to-skin moisture, while rib-knit weave creates dead air space for added insulation and natural stretch for movement. Crew collar provides a comfortable neckline that flatters and layers easily. Center-front seam for shaping. Wide self-fabric cuffs and hem. Nau M1 Rib Crew has a trim fit. Machine wash cold, delicate cycle, line dry; cool iron back side of fabric if needed.