Smartwool Men's Teller Tech Tee Knit in Vietnam of 75% Merino Wool, 25% Polyester Semi-Form Fit Merino Max Eyelet and Jersey Knit; UPF 37 Eyelet knit body for ventilation and breathability combined with Jersey knit shoulder and side panels for increased durability Hidden internal sunglass wipe panel at wearer's left hem; Side panels eliminate true side seams for reduced chafing