I don't know about stocks at all. They probably ventilate them in a way t hey think most people who wear hair wear them. Not sure, but when I specified how I wanted the hair to be vented on a custom order, they did it perfectly. The hair goes easily back in the front, which I always had a problem with.. The front hairline and temple flaps were ventilated Really nice, that was what i was most impressed about.. but again this was a custom order.