What Our Gearhead(R) Experts Are Saying:"I wore the 300 MerinoFine Polar Long-Sleeve 1/2-Zip on the coldest day of the season and it felt softer against my skin than any base layer I've owned. The half zip let me dump heat on the skin up without ever stopping to peel off a layer."The coldest days need a base layer that actually holds up, and the Icebreaker 300 MerinoFine Polar Long-Sleeve 1/2-Zip is built for exactly that kind of morning. This is the layer we reach for before dawn patrol laps or a full day riding through single digit temps, ultrafine merino fiber feeling soft against skin rather than scratchy the way heavier wool sometimes can. A half zip lets heat escape the second the effort ramps up, and thumb loops keep sleeves anchored through every pole plant or grab. Flatlock seams and a zipper chin guard cut down on friction where it matters most, and a drop tail hem adds coverage right where a jacket tends to ride up.