Comfort
The wool/polyester blend gives the Smartwool PhD Utra Light a completely different feel than all other running tops. Reminiscent more of a ski top than a running top, the wool blend looks and feels closer to a wool shirt verses a typical polyester running top. While the fabric is incredibly soft, those who find wool irritating may want to avoid this one.

Fit
Smartwool lists the Ultra Light Tee as regular fit, however compared to others tested, the body fits closer to a slim fit. The body length was on the longer side compared to the others, dropping well below the waist, but not dramatically so. The sleeves are also on the longer side, which is a bonus on cooler days when pulling the sleeves over the hands is an option.

Wicking Ability
This one topped the charts in its ability to wick and absorb sweat. The addition of wool adds a level of temperature and moisture control most polyester blends don’t offer. However once wet, the shirt retained moisture and drying times were much longer than others.

Warmth
In terms of retaining body heat, the PhD Ultra Light Tee performed flawlessly and offered more warmth than any other top in the test.

Features
Smartwool’s PhD technology is the main feature of the Ultra Light Tee, which gave it superior temperature and moisture regulating properties. To enhance breathability, Smartwool includes body mapped mesh panels in high heat areas specifically mapped to gender.

Durability
The Smartwool Men’s PhD Ultra Light Long Sleeve proves to be a contender for most durable of the test. The PhD fabric held up quite nicely over time and during our abrasion test. There were no signs of the stitching pulling or unraveling. The only indication of an aging top was the loss of some elasticity.

Fabric: Body – 56% Merino Wool, 44% Polyester; Mesh – 54% Merino Wool, 46% Polyester