Good running top. Has back and under arm venting, which allows you to dump very heat fast. However the fit is kind of odd. I wear a Nike size large. The chest and length fits perfect, the arms are a bit loose, and the midsection is very loose and boxy. That may be because it's purposely designed for maximum airflow. However I would prefer a tighter fit in the midsection. Also the shirt is highly overpriced, so purchase only while on sale.
