Did not overheat!
"I took this hat out for its first run on the weekend, covering 22 km on the Sunshine Coast, and it quickly proved itself to be a great choice. The hat is very lightweight and comfortable, while the brim has enough structure to resist flapping around in windy conditions. The fit is highly adjustable, so it stayed secure the entire run. Most importantly, I never felt like I was overheating. In fact, the ventilation worked so well that the longer I ran and the sweatier I got, the cooler and more comfortable the hat felt. I was so impressed that I immediately messaged a mate who I'd previously asked for running hat advice to tell him how good it was."