Specifications:- Size: S- Fits Head Circumference: 21 5/8"" to 22 1/16"" (55 to 56 cm)- Overall Dimension(LxWxH): 11 13/16"" x 8 7/8"" x 6 11/16"" (30 x 22.5 x 17 cm)- Net Weight: 2.43 Lbs (1.1 kg)- Material: Abs, Eps. Package Contents:- 1x Helmet- 1x Bag- 1x Epe Bag. Notice: - Before purchasing, please measure your head's circumference to determine which size is suitable for you.- Here's the way:- Wrap the flexible measuring tape around your head.- Position it on the broadest part of your forehead above eyebrow and the most prominent part of the back of your head.- Make sure the measuring tape lays flat against your head but doesn't pinch. It should be level all the way around.