Features: 1.Adopting one-pieces molding process, uniform force is not easy to break, and effectively protect the safety of rideres. 2.The ventilation holes can help the head to wicks away perspiration and dry quickly, and it is refreshing and not stuffy, and it reduces wind and shade, and breaks the wind to ride more smoothly 3.Red plastic joint, 11cm telescopic, can meet most head circumference with one-handed operation and 360 degree adjustment 4.Detachable and comfortable inner lining, easy to clean and keep the head fresh 5.Padded breathable holes, with good sweat absorption ability, can be removed for cleaning, more hygienic, convenient and smooth, high-quality buckle, quick to take off, no buckle Notice: Actual color may be slightly different from the image due to different monitor and light effect Please allow 1-3cm deviation due to manual measurement Description: 1.Product name: bicycle riding helmet 2.Model: adult helmet, both male and female 3.Size: all sizes, regardless of size 4.Helmet outer size: about length 28*width 21*height 15CM, suitable for head circumference between 57-62cm, head width within 18.5cm, head length 23cm, with adjuster knob, adjustable head circumference size 5.Material: EPS foam PC sheet, built-in sweat-absorbing lining, nylon webbing and PP material regulator 6.Wind tunnel: 18 wind holes 7.Color: multi-color optional Package List: 1*Bicycle Helmet