Light material for hot weather (not good if you are rubbing against concrete walls all day, but great for normal use).  Polyester so that it doesn't soak up and display sweat stains.  The style and color of the dark blue and white means that it isn't to "camp shirt" looking for casual wear.  I have 4 in dark blue and 4 in white, which I've purchased over the years.  You might try a different, thicker shirt if you need more durability e.g. camping, landscape work, construction, etc, but those shirts don't breath as well.