Built for Speed: the Vento KinetiCore was designed with a reduced frontal surface area for superb performance in a “sprint position” at a 15-degree angle Find your size: Measure the circumference of your head 2cm above your eyebrows (about the width of a finger). Once you have your head circumference, use our size guide to select the correct size based on the model helmet you are interested in. If you are between sizes, we recommend that you select the smaller size helmet Lighter by Design: Vento is 24% lighter and uses 90g less plastic than its predecessor, and is built more sustainably with a reduced carbon footprint without any compromise in performance. The Power of Cool: cleverly-positioned ventilation channels increase airflow through the helmet to enhance cooling, elevate your comfort and performance Precise Fit Comfort: Advanced ScrollSys fit system cradles the skull while allowing intuitive, quick adjustments for a precise, stable fit Reduced profile, engineered airflow. Vento KinetiCore delivers the best combination of protection, ventilation and aerodynamics.