Neleus Men's Workout Athletic Compression Shirts Pack of 3 85% Polyester / 15% spandex, Machine Washable Made in USA or Imported Elastic closure Size is comparably smaller,So ignore Amazons's size chart,please kindly refer to our suggested chest and the actual measurement; If you do not know your measurement chest size or you prefer the "Less Tightly Fit",please order 1 SIZE UP than you normally wear Tight Fitting,like a second skin.Please order 1 SIZE UP than you normally wear if you prefer less tightly fit Moisture Transport System sweeps away sweat and dries quickly; Flat lock seams to prevent chafing Suitable for all sports indoors and outdoors,such like:running,basketball,cross training and etc Ergonomic compression fit for enhanced range of motion