Smartwool Classic All-Season 1/4 Zip Merino Base Layer - Men's Black Medium. This top uses our All-Season-weight Merino fabric wrapped around a nylon core to increase durability while still keeping the 100percent soft Merino wool you love next to skin. Side seams help minimize chafing while wearing a pack and offer a body-enhancing fit. This base layer is comfortable powerful sustainable and frankly do-it-all-able. Specifications for Smartwool Classic All-Season 1/4 Zip Merino Base Layer - Men's: Manufacturer: Smartwool Age Group: Adults Apparel Fit: Slim Gender: Male Color: Black Application: Outdoor Fabric/Material: Recycled Nylon Merino Wool Features of Smartwool Classic All-Season 1/4 Zip Merino Base Layer - Men's Our lightweight Merino jersey fabric uses a recycled nylon core while still keeping 100percent Merino wool next to skin Package Contents: Smartwool Classic All-Season 1/4 Zip Merino Base Layer - Men's Smartwool SW002819001100M000: Classic All-Season 1/4 Zip Merino Base Layer - Men's Black Medium