The North Face Isotherm Long Sleeve Review

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High intensity activities during the cold weather months demand smart moisture management and warmth. The North Face developed the Isotherm Long Sleeve to meet these exact requirements. As a daily runner that gets outside, no matter what the temperatures are, I am always seeking gear that can help keep me warm and dry, when conditions are less than desirable, including below 0F.

Isotherm Long Sleeve Fabric

I have been testing TNF Isotherm Long Sleeve on runs of up to 3 hours, full day touring adventures on skis and snowshoes, and as a base-layer during downhill ski days. The Isotherm Long Sleeve includes a medium weight merino wool in the front/chest, torso, and top of the arms. High heat producing areas feature The North Face FlashDry fabric, which is lighter weight. The FlashDry fabric is designed, as its’ name suggests, to accelerate the movement of moisture on the skin and expedite evaporation and drying. This translates into keeping you dry, no matter the weather conditions and your level of exertion. Flat lock seams ease the transition from merino wool to FlashDry fabric with ease. These seams avoid high friction areas, such as under the arms and along the sides.

Sizing and Style

The North Face Isotherm Long Sleeve is available in three color combinations. The main body of the top utilizes the same color, despite the fabric type, and the flat lock seams provide a splash of accent coloring. The Isotherm Long Sleeve is available in Pixie Purple with a hot pink stitching, TNF Black with hot pink stitching, and Meridian Blue with lime green stitching. The top features two reflective logos to increase visibility in dark winter months: on TNF logo at the left front chest and another Flight Series logo mid-shoulder region on the rear of the top.

The center back length is 25.75 inches, which is plenty of length to tuck the shirt in, if you wish to do so. The sleeve length is quite generous, without feeling too sloppy. The top is semi fitted and layers well under additional garments, while running true to size. The Isotherm Long Sleeve is available in size XS to XL.

The North Face Isotherm Long Sleeve has been my go to piece day after day, as I can get a few wears in a row between washes, thanks to the natural anti-stink properties of merino wool and the FlashDry fabric which equates to quick drying. For more information about this top and FlashDry, please visit www.amazon.com/thenorthface.

MSRP $90