The Petzl Boreo climbing helmet is available in sizes ranging from 53 to 61 cm. Given that your head circumference measures 57 cm, this size should fit you perfectly. The helmet is designed to fit different head sizes in this range, so you should be comfortable with this size range.

According to the supplier, the helmet is actually unisex and it really only depends on the head circumference. Thank you for letting us know. We will be happy to pass this on internally to the relevant department and hope that this will be adjusted promptly.