The Giro Atmos continues to set the standard for high performance, matchless style, and a comfortable fit. It's low profile silhouette, 26 Wind Tunnel vents, and carbon reinforced Roll Cage make it a top choice for road, cross, and XC riders alike. Updated with Giro's Roc Loc 5 retention system, tension adjustments can now be made single-handedly in seconds with the turn of a small dial. CPSC Certified. SM (51-55cm), MD (55cm-59cm) or LG (59-63cm).