The Arc&';teryx Rho SV Zip Neck is a heavyweight base layer top engineered for cold-weather activity. Its warm, moisture-wicking fabric and zip neck deliver next-to-skin comfort and easy temperature regulation, making it an ideal foundation layer for winter pursuits. Heavyweight, warm base-layer fabric Moisture-wicking and breathable for high-output cold-weather use Zip neck for quick venting and temperature control Flatlock seams reduce chafing under layers Trim fit layers smoothly beneath midlayers and shells