Ekoi Helmet Used only for a fitting, so please understand that it is a used item. JCF-approved model Size: M (55-59cm) The chin strap buckle has a magnet, so it can be easily locked with one hand. I have been using other Ekoi helmets before, and they are convenient. The following is an excerpt from the manufacturer: The Ekoi CRISTAL is the latest model that combines safety and light weight, using a polycarbonate cage. It features a racing design and a sturdy polycarbonate frame, as well as large ventilation. With 18 ventilation functions, it is a model that can be used comfortably throughout the year.