The FIRST and ONLY helmet to fully integrate the best of high impact absorbing EPS Foam with thick dual density soft foam and plush Sweatsaver fabric, delivering the ultimate in comfort with dual certified protection. To ensure a perfect fit, measure the circumference of your head starting in the middle of your forehead and match it with the sizes below: XS/S 20 - 21.25 in (51 - 54 cm) S/M 21 - 22.5 in (53 - 57 cm) L/XL 22.5 - 23.5 in (57 - 60 cm)