Made for Epic Days: From the toughest road races to the rowdiest gravel adventures, the Z1’s ideal balance of light weight, ventilation and protective performance is second-to-none. 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 Precise Fit Comfort: Advanced ScrollSys fit system cradles the skull while allowing intuitive, quick adjustments for a precise, stable fit The Power of Cool: massive ventilation channels supercharge airflow through the helmet to enhance cooling (the Z1 is up to 3% cooler than not wearing a helmet at all!) Lightweight Leader: among the lightest in its class at 220g (size M) yet fully-featured with leading protective capability Lightweight, maximum ventilation, guaranteed comfort and enhanced protection. Z1 KinetiCore is all you need in a performance helmet.