The highly refined construction and fabric of this Regulator® fleece traps heat and breathes freely to keep you warm and comfortable across a wide range of conditions. The main body relies on high-loft R2® fabric (Polartec® Thermal Pro® 63% recycled polyester), which is superlight, wicking, compressible, stretchy and soft. R1® Polartec® Power Grid® high/low grid panels run along the underside of the upper arms and down the sides of the body to improve fit, mobility and comfort range. The lower arms use cozy R2® fabric, and the softly lined inner collar and kissing-welt zipper garage go easy on the neck and chin. Other details: Sonic/Stitch seam construction on all zippers reduces bulk, while raglan seams enhance mobility and comfort. Slim zippers close the sleek handwarmer pockets; the handwarmers’ pocket bags double as stealthy internal mesh drop-in pockets.