Features of the Smartwool Men's Merino 150 Pocket Tee Our lightest weight Merino jersey fabric Uses a nylon core to increase durability while still keeping 100% Merino wool next to skin Offset shoulder and side seams designed to increase comfort and minimize chafing while wearing a backpack Front chest pocket UPF 20+ Fabric Details 87% Merino Wool, 13% Nylon