The Giro(R) Adult Isode(TM) Bike Helmet offers a simple design with maximum safety. It offers, MIPS technology, 22 vents, and quick-drying padding. The in-mold polycarbonate shell with EPS foam liner provides optimal durability. Quickly adjust the fit of the helmet with the Roc Loc(R) Sport fit system. FEATURES: Designed for recreational biking Compact shape design Multi-Directional Impact Protection System reduces rotational forces from certain impacts and offers more protection Roc Loc(R) Sport fit system allows you to adjust the size with one hand and has a 7cm adjustment range with a clicking sound for a comfortable fit Ventilation: 22 vents Full Hardbody(TM) shell for greater durability and protection In-mold polycarbonate shell with EPS foam liner provides strength and impact absorption Quick-dry padding adds comfort Reflective features increase safety and visibility Complies with U.S. CPSC Safety Standard for Bicycle Helmets for persons age 5 and older SIZING: Universal Fit Sizing: 21.25" - 24"/54-61cm