I didn't have high expectations for this cap. But, I was pleasantly surprised once it was snuggly on my bald head. I wear something under my helmet almost every ride to prevent "grill marks". My goto was my Castelli summer cap or summer band. The Giro feels like it is a part of my Giro Syntax helmet. It is not to big or bulky. It has a perfectly-sized brim, breathes, and is soft to the touch. I'm considering a 2nd or 3rd.
Update: After a few sessions on my indoor trainer, I'll add absorbs sweat like a sponge.

I'm a sweater, and due to some pasty skin I also could get a sunburn from a night-light. Having short hair i'm always concerned about getting the top of my head burnt so I've tried everything from baseball caps to bandanas on my head while i ride.

The thin fabric fits great under my road helmet and is very breathable. It doesn't have the heaviest sweat band but this works in it's favor as it makes it very comfortable to wear. I wore it on a 60 degree day and my head was actually cold.

I have used it for running and cycling works great for both.

It is hand-wash only.

I would definitely recommend.