The Radix™ combines rugged style and durability to meet the demands of core trail riders, with the coverage, light weight and ventilation riders need to ride comfortably and confidently, all day. The highly adjustable Roc Loc® 5 system allows you to customize fit/feel for enhanced stability and long-range comfort. The P.O.V.™ visor offers 15 degrees of adjustment, and the tough polycarbonate outer shell is fused permanently to the EPS foam liner using Giro\\\'s In-Mold™ construction process, to enhance durability and ventilation without excess bulk. Key Features Full-wrap In-Mold polycarbonate shell with EPS liner ensures continuous protection without being bulky or heavy Extended coverage for back of the head protection, essential for the unpredictable nature of MTB falls Adjustable P.O.V.™ visor helps shield your eyes from the rain or sun 25 Wind Tunnel™ vents for a cool and comfortable wearing experience Cool-fit anti-microbial padding for added comfort and hygiene The Giro Story - WE\\\'LL STOP WHEN YOU STOPYou, doing things that most people wouldn\\\'t even consider. Drawing a line that\\\'s rarely inbounds. Descending at speeds that would give your underwriter pause. Pushing yourself in ways nature and gravity never intended. As long as you\\\'re relentlessly pushing forward, we will too. When you stop, that\\\'s when we\\\'ll stop. We\\\'re obsessing over your passion. Destroying more helmets in testing and development than some brands even create. We\\\'re agonizing over vent sizes and inseam lengths. Pouring our years, our hearts, our sweat, into one insole, one goggle, one helmet at a time. Plainly said, being there when you need us most. Giro Helmet SizingSMLXLHead Circumference (CM)51-55cm55-59cm59-63cm61-65cm Helmets Buying Guide