The fabric is light weight and quick drying but NOT sheer or see-through. The mesh fabric on the back and under the arms does provide a bit of extra air flow. I am between size small and medium (height 5'6", weight 120). In this case I got a medium for a looser fit. The color is slightly different than shown online (the blue color has higher contrast stitching on the seams and mesh fabric under the arms and on the back), but I can live with that. I liked this shirt so much I ordered a second color!