The 10 Best Long Underwear Sets

Norwegian 400 gsm double-face wool. The warmest true base layer sold, and it dries fast for the weight.

Norwegian Merino with flatlock seams that vanish under a hipbelt. The all-day winter set.

The benchmark 200-weight Merino — the layer you can wear for a week and still be tolerable.

The best-cut 250-weight in the US, with a body-mapped fit that never rides up.

Austrian Merino with mesh panels where you overheat. Best for hard uphill in cold air.

Swedish terry-loop wool worn by arctic militaries. Loft that survives repeated washing.

The Norwegian mesh string layer — bizarre-looking, unmatched moisture handling in deep cold.

The synthetic benchmark: grid fleece that dries faster than anything wool on this list.

New Hampshire Merino at half the price of the imports, with the same 18.5-micron feel.

Montana wool grid, US-milled end to end. The best hybrid layer for high-output winter days.