The chin strap has been cut a little, so please consider it a junk item. It has been used about 4 times. Thank you. The Giro Eclipse Spherical helmet is a medium-sized cycling helmet with an antibacterial structure and excellent ventilation. - Brand: Giro - Model Name: Eclipse Spherical - Size: M (55-59 cm) - Features: Antibacterial structure, multi-layer construction, ventilation - Application: Cycling helmet Thank you for looking.