ASICS Men's Favorite Short Sleeve Running Shirt 100% polyester Fabric Type: Interlock--A type of double knit with a smooth surface on both sides Fit: Semi-Fitted--Slim, contoured fit for ease of movement and a stylish look. Fabric Type: Mesh--A knit or woven fabric with small, evenly spaced holes Performance Technology: ASICS Hydrology--The fabric absorbs sweat from the skin, then transfers it to the surface where it can evaporate rapidly. Hydrology fabrics provide breathability and air circulation, and most provide UV protection between 15 - 40 UPF. Anti-Microbial--Anti-microbial treatments provide permanent odor protection by inhibiting the growth of bacteria and mildew in the fabric.