The Women's All Season Long Sleeve 1/4 Zip Baselayer is made from Smartwool's lightest weight Merino which is wrapped around a nylon core for extra durability. This composition allows for 100% Merino wool next to the skin for ultimate comfort as you traverse through the hills. The baselayer is flattering on all body types and is made from Merino 150 which is super soft, lightweight and breathable. It offers a full range of motion and is breathable so sweat can move away from the body, making it the perfect layer for warmer conditions. Slim fit - flattering on all body shapes, follows the contours of the bodyLightest weight Merino jersey with a nylon core - increases durability while still keeping 100% Merino wool next to skin for comfortMerino 150 - breathable, soft, lightweight fabric offers next-to-skin comfort, moves sweat away from the body, and acts as a versatile performance layer for warmer conditionsStretch merrow stitching designed to elevate comfort, range of motion, and fitPrincess seams on front and back panels designed for figure-flattering fit8.25" (21 cm) center-front zipper with semi-locking sliderMaterial: 88% Merino Wool, 12% Nylon (exclusive of decoration)Colour: Light Grey