The Fox Speedframe Pro is a top-shelf open face trail helmet offers a market leading feature set including MIPS rotational management system, an easily adjustable multi-positon visor, a 360 degree retention system and Fox's proven dual-density Varizorb impact absorbiong EPS liner. MIPS added protection system has been proven to reduce the rotational motion when implemented in a helmet by absorbing and redirecting energies and forces otherwise transmitted to the brain Dual-density Varizorb EPS provides improved protection by spreading forces of impact across a wider area Fidlock® SNAP helmet buckle provides quick and secure entry and exit while wearing gloves Removable, washable XT2® liner is antimicrobial and manages odor while wicking moisture away from the head Optimized venting with channeled, in-molded EPS provides efficient cooling Goggle compatible, 3 position adjustable visor 360°Fit System allows you to dial in your perfect fit every ride SIZING: Using a tape measure, measure the widest circumference around your head.Small: 55cm-65cmMedium: 57-58cmLarge: 59-60cm