Excellent features like our 4th dimension cooling system and patented clip on visor plus certified protection and sleek styling make the chamonix a terrific value for any cyclist one size system designed for easy and accurate fit to a wide range of head sizes headset sx fit system with micro adjustable dial for easy secure and accurate fit 4th dimension cooling system optimizes ventilation in moulded shell improves strength and reduces weight tri fix web splitter for improved comfort a