Smartwool Classic All-Season Merino Base Layer Crew - Men's Nightfall Blue Extra Large. The year-round Men's Classic All-Season Merino Base Layer Long Sleeve is game for either. With our Core Spun technology we've wrapped lightweight Merino around a nylon core for added durability while still keeping the comfort of ultra-soft responsibly-sourced Merino next to skin. We added smooth flatlock seams to help minimize chafing and offset shoulder and side seams to lie smoothly beneath pack straps. No matter the season or the activity this base layer is made for it. Specifications for Smartwool Classic All-Season Merino Base Layer Crew - Men's: Manufacturer: Smartwool Age Group: Adults Apparel Fit: Athletic Gender: Male Color: Nightfall Blue Application: Outdoor Features of Smartwool Classic All-Season Merino Base Layer Crew - Men's: Our slim fit is intended to follow the contours of the body. Our lightweight Merino jersey fabric uses a recycled nylon core while still keeping 100percent Merino wool next to skin. Flatlock seam construction and offset shoulder and side seams designed to help increase comfort and minimize chafing. Side seams wrap to front. Made in Vietnam: 88percent Merino Wool 12percent Recycled Nylon. Exclusive of Decoration. Package Contents: Smartwool Classic All-Season Merino Base Layer Crew - Men's Smartwool SW016952P4310XL000: Classic All-Season Merino Base Layer Crew - Men's Nightfall Blue Extra Large