This is a Filson Twin Lakes button down outdoors shirt in a size medium Constructed with an ultralight blend of polyester and nylon, the Twin Lakes' fabric wicks moisture away from the body for rapid evaporation. The vented back yoke sports a mesh underlayer, allowing heat to escape and allowing the breeze to provide natural cooling. Under-arm embroidered eyelets provide further ventilation. Unlike ordinary synthetics, this performance fabrics is treated and tested to provide UPF30+ sun protection to prevent the harmful effect of ultraviolet rays on unprotected skin. And with an antimicrobial finish, there's need for concern about the perpetual odor that can build up in lesser fabrics. Made of 53% polyester and 47% Nylon Measurements are 23.5 inches in the front from pit to pit Length is 30 inches B-1 Mens Shirt