SmartWool NTS Microweight 150 Short Sleeve Running T-Shirt 100% Merino Wool - Knitted in Vietnam, Merino wool is nature's most technical, high-performance fibre. Its complex structure retains heat superbly and feels decadently soft against the skin. Functional Fabrics - Merino wool regulates body temperature, heart rate and deposits due to its natural moisture-management and thermoregulation properties. Interior Flatlock Seams - Provides additional comfort and helps to prevent the risk of chafing. Stripe Tape Binding - Positioned across the neck to enhance comfort whilst in motion. UPF 30 Rating - This garment delivers effective protection from harmful UV rays.