Smartwool Women's Outdoor Clothing . Sustainable fashion and apparel. Smartwool Classic All Season Merino Base Layer Long Sleeve Women's Women's Classic All season Merino Base Layer Long Sleeve Women's merino wool base layers & thermals Smartwool Women's Plus Size Classic All Season Merino Wool Base Layer. An all season favorite, the Women's Classic All Season Merino Base Layer Long Sleeve can be sported as a base layer in the fall or summer when it's time to go backpacking. This base layer features Core Spun technology??? which is Merino wrapped around a nylon core for added durability while still keeping the comfort of ultra soft, responsibly sourced Merino next to skin. Our Raglan sleeves eliminate shoulder seams for perfect comfort under a pack, and smooth merrow stitching wraps from side to front to keep you looking as good as you feel.