Why do you need a helmet?Cycling is fun, is healthy. But an accident or fall can quickly lead to serious head injuries. Modern bicycle helmets. They protect effectively and reliably in the event of an accident.How to choose the right size?To find out the size of your head, wrap a soft tape measure over the eyebrows and ears.Make sure the tape measure is at the same height from the front to the back of the head.A helmet should fit snugly all around, without gaps between polystyrene and head, not too tight or loose.Small: 52 cm - 55 cm (20.5 - 21.7 inches) for children.Medium: 55 cm - 58 cm (21.7 - 22.8 inches) for teenagers.Large: 58 cm - 61 cm (22.8 - 24 inches) for adults.Note:Please measure and confirm your head size before purchasing.Start with the right size, if you have any questions about size, you can contact us.Warning:Automoness skateboard bike helmet is designed to withstand more than a light shot. However, a skateboard helmet must be replaced if it is tangled in a heavy fall or is damaged.Never apply paint, detergents or other chemical products.Never apply self-adhesive. Size:Â Medium: (55-58cm/21.7-22.8in)