In-mold design.18 Ventilation holes.Back vents for optimal airflow.Mesh in the vents protects against insects.Adjustable straps for a perfect and comfortable fit on the head.TwistClose clamping system can be easily adjusted with one hand.Washable antibacterial linings.Removable label for easy use for MTB and roadBack reflective stickers.Sizes: M (54-58cm) and L (58-61cm).