Make & Model - Mammut Klamath Half-Zip & Long Underwear Bottoms
Fabric - Polartec Power Wool 145 Jersey, 31% wool / 69% polyester
Weight - 6.4/4.9 ounces (medium)
Colors - Gray, Navy
MSRP - $99/$79
URL - http://www.us.mammut.com

Compared to the other Polartec Power Wool product in our roundup, Mammut's Klamath baselayer Fabric is thinner with a lot more stretch and return. It fits snuggly in all areas of a healthy, one-time athletic, 46-year-old male body without bunching or constricting. It's served well as a base layer for a 15 degree F range day (no prone shooting!), felling trees in 6 inches of snow, and a dozen days of ski patrol work.

The delta between pulling sleds loaded with 200 pounds of injured guest across a flat and riding a chairlift in barking snow is more than a fair test of breathability. Mammut's Power Wool construction managed to keep the air moving while working, and the sweat from freezing while riding the chairlift on the lift. The deep zip collar helped dump heat when needed, and the smooth face Fabric never bunched up on the softshell pants worn atop it. The seams could be positioned out of the armpit. But as we understand it, the Power Wool Fabric is pricier than regular wool and wool blends, so we can live with Mammut's decision to spend the money on the Fabric instead of adding seams and sewing time.

Pros:
– Frictionless base layer works great with over layers
– Warmth without clamminess
– Fabric panels match articulation well

Cons:
– Thin waistband tends to roll
– Seams fall in high wear/high chafe areas
– No pee slot