The Nine Helmet offers timeless style with a tried and true design. The in Form Fit System makes it easy to dial in a perfect fit, while the super cool vents ensure fresh air so you can stay comfortable on the slopes. The Nine helmet offers a wealth of features, including the custom tuning of the In Form Fit System and Thermostat Control venting so your noggin doesnt get too stuffy. Experience the Nine for yourself, and youll see why its one of the most enduring and popular performance snow helmets available. Stack Vent Technology was developed based on research the majority of warm air that can cause fogging comes from the goggle's center top vent. Aligning the Stack Vent in the helmet with the center vent of the goggle helps keep it clear and fog-free. Seamless Compatibility: for optional performance of both helmets and goggles, Giro helmets are designed to work together, ensuring a seamless inerface between helmet and goggle for an exceptional fit and dependable, worry-free function in Mold Construction fuses a tough polycarbonate outer shell with the helmet's impact-absorbign foam liner. The fusion process allows for better ventilation systems, making in-mold helmets lighter and cooler than traditional helmets.