SmartWool PhD Running Shorts 100% Wool Woven Outer Short - And a fitted Merino Wool internal brief provide ultimate support with the 4-Degree Elite Fit System. Seamless Construction - In the brief, with knit-in ventilation in high heat zones. Secure Back Pocket - With semi-auto locking zipper pull. 360 Reflectivity - For visibility even in low light. Material - Outer Short - 100% Recycled Polyester; Liner - 79% Merino Wool, 18% Nylon, 3% Elastane