We're going on a trip to the Southwest, and being all red-heads, we need serious sun protection, so I thought I would try these shirts. I am a mom, but I didn't like the fit of the women's style, so I bought a men's X-Small.  I tried it on when I got for sizing, and although it was a little tight across the chest (I'm relatively flat, 5'6", 120), the shoulders and other lengths were good (small had been very baggy in every way), so I kept it.  However, yesterday I put it on again to check layering, and the lighting must have been very different from when I tried it on for size, because without even trying hard, I could see right through it in the mirror.  Haven't seen how effective these are against the sun yet (trip is still upcoming - the rest of my family will try theirs), but I'm returning mine.