i have many polyester shirts, from cold weather to these workout shirts. first off, never ever ever put these in the washer or dryer. wash them in the sink, wring them out, and hang them to dry if you want them to last. even my very expensive cold weather shirts catch snags from other things in the wash. these are by far the best at keeping you cool and dry. i even wear them as an under shirt with my work shirts to keep me from sweating so much. i purchased one on a whim and when it became my favorite running shirt, i purchased more. i usually have trouble with sizing, i am 5'10" 188lbs (muscular build) and wear a M or L t-shirt depending on the fit. with these i wanted them form fitting and the medium exceeded my expectations and fit perfectly, which never happens.