I have what I call a "normal" sized head; all helmets size L are plenty big for me. But even in the larger size, this thing fits like a yarmulke. The De Soto beanie (also sold here) is perfect, so I imagine the folks who rate this Assos cap as acceptable must think the De Soto cap is way too big. But I like the cap to come down to my brow, and to come down far enough in the back to be under the helmet adjuster strap. That's how these things work to keep sweat out of your eyes. Also, I did not use it, but the fabric seems really thick for summer use. Again this is where the De Soto is perfect.
I was tired of the Arizona sun leaving vent stripes on my shaved head and the sweat pouring into my eyes. Caps are too hot for riding in the summer so I thought I would try this robo foil (whatever that means). My head actually feels cooler wearing it than not, under a helmet and while I'm riding. I don't think I'll wear it out to dinner though. Its lightweight, breathes like Egyptian cotton and keeps my head cool while doing something with all that sweat that used to run into my eyes. There are no uncomfortable seams nor does it feel like cheap fabric. Its made hot summer rides easier.
I have bought a second Assos ASSOSOIRES Robo Foil G2, because my first one worked so well in the summer's heat. No sweat running down my forehead and into my eyes with this cap, even on a long day in 92-degree, high humidity weather. Great fit and stretch.