As the choice of pros around the globe, the Helium has proven itself time and time again on the hardest stage Decidedly comfortable and secure utilising the Rollsys Retention System, as well as the X-Static Padding providing temperature regulation. As with all Lazer helmets safety is key. The Rigidity Brace System (RBS) features internal structural reinforcements that channel and dissipate energy for increased protection in multi-impact situations. Lazer Roll-sys retention mechanism: The Roll-sys retention system gives you accurate and progressive sizing adjustment using a unique roller at the top of the helmet, allowing you to easily alter your fit with one finger, even while riding. The roller regulates the tension of a cable that is routed around the entire circumference of the head, giving totally even retention without pressure points or pinching. The system automatically centres the helmet on your head an also accommodates ponytails. Roll-sys is patented by Lazer and on - Fit System: Rollsys Retention System - Rigidity Brace System (RBS) - Magneto Magnetic Attachment System - Construction: Inside In-Mold (7 pieces) - Double Density EPS: Lighter and denser weight foam - Ventilation: 19 vents - X-static padding - Certification: CE - CPSC - AS . Size: Small (51-53cm)