Prexport boasts that this boot also has the best ventilation system on the market. There is an adjustable air scoop on the side of the foot. The air flows through channels built in the boot which lead the air around the side of the foot, up the ankle and out the exhaust vents about mid-calf. You can feel these channels from the inside of the boot. The design looks to be similar to those built into high end helmets.
Closure is on the inside of the foot with a zipper and leather velcro-close flap over the zipper.
If anything they run a bit on the small side, so if you are between sizes, then go up to the next even size rather than down. PTBS09 - . PTBS12 - . PTBS12 - .