The XL fits my watermelon sized (61cm) noggin loosely enough to slip three fingers under the brim. That's rare and good. The sides are nice and deep, similar to the Korean war style fatigue caps and so it sinks down until it sits on right on my ears. I like that.

It's pretty light (56g).  It's nicely made.  Although it has "Outdoor OR Research" embroidered obnoxiously and non-removably on the left front side it's not nearly as offensive and hideous as the huge "OR" that Outdoor Research usually plasters it's hats with. There is another "Outdoor Research" label sewn to the outside rear of the hat; this is (and will be) easily removed.  If OR is going to charge me to advertise for them they could have at least stitched this rear label in such a way as to make it useful for hanging a small strobe light or turkey feather.

The folding brim works well; the brim is reinforced with stiff, curved inserts of perhaps plastic but possibly cardboard. Fits folded in a hip pocket comfortably. There's a 10cm cord loop stitched to the inside rear crown.  I don't really know why it's in that particular location as it seems an awkward spot from which to either hang or tie town the hat.  The 4cm exterior band is double fabric and appropriately stiffened, perhaps with facing or scrim, to give body. This is good as the rest of the cap fabric is rather soft and shapeless. The 4cm interior band is  a black,soft and absorbent thin fleece.  The bands together are somewhat warm but they do move moisture well and keep sweat off the face.

Here's the problem.  The body of the cap, both sides and crown, are made from a double layer of Supplex-like nylon. I have no doubt it blocks sunlight at the proclaimed (and embroidered) 30SPF rate.  However, it doesn't breath well at all. I have waterproof jackets that huff-test with more air permeability. Now in my experience, and especially here in Florida, very often when it's sunny it's also HOT.  And when it's sunny, and hot, and especially when it's humid, I find that air moving around my head is critical to being comfortable. I guess I'm funny like that. This cap fails miserably at letting hot air convect away from my head.

So in conclusion this is probably a good cap for a very narrow weather range.  If it's cold and sunny or cloudy you'll want something that'll keep you warmer.  If it's sunny and cool this is a good hat. If it's sunny and hot you risk heat exhaustion wearing this for anything other than sitting in the shade staring at your cellphone. If it's cloudy and hot you'll be miserable with this thing on.

I am seriously considering cutting some ventilation holes in the inside layer of fabric.