Vented Hairbrush Bristle is used to help in drying your hair, combination with your hair dryer.
It is also used as a styling tool. It's great at light styling and drying hair because the bristle count is very low as compared to other brushes. The lower bristle count allows air from your hair dryer to reach you hair through the vented brush. Your hair dries faster. The vented brushes have just enough bristles to provide tension for light styling and volumizing.