Certification: CE - ASTM - FIS The HERO 9 helmet conforms to FIS regulations, offering 50% greater protection against impacts. Hard Shell ABS technology offers enhanced durability while Air Flow ventilation allows constant air circulation for increased comfort and temperature regulation. The reduced volume and compact design controls weight and fits closer to the head for aerodynamic racing performance. Chinguard included. RACE FIT offers a precise fit, full-shell design with fixed ear pads, enveloping the head up to the cheeks. Our HARD SHELL construction features an external 3mm ABS shell with separately injection molded PSE, allowing easier incorporation of vents and less visual affects due to light impacts. A good-fitting helmet shouldn't compress your head, but should remain well positioned when/if your head is shaken. You can use a tape string or our Head Sizer to measure the circumference of your head, passing over your ears and staying 0.78 inches above your eyebrows. Many of our helmets have a knob to adjust and fine-tune the fit for additional comfort and safety. Ideally, with the helmet on, you should be able to twist the helmet forward and back and see your eyebrows moving along with it. If the helmet slides forward or back too easily and/or without eyebrow movement, it's not providing the ideal fit.