Specifications:- Overall Dimension(LxWxH): 11 1/8" x 9 1/8" x 6 9/16" (28.2 x 23.2 x 16.7 cm)- Size: S- Fits Head Circumference: 21 5/8" to 22 1/16" (55 to 56 cm)- Material: Abs, Polyester- Net Weight: 2.1 Lbs (0.95 kg). Package Contents:- 1x Helmet- 1x Bag- 1x Epe Bag. Notice: - Please measure your head's circumference to choose the size that is suitable for you. Here's the way: Wrap the measuring tape around your head and position it on the broadest part of your forehead above eyebrow and the most prominent part of the back of head.