Made of special polymer material, it is resistant to repeated sterilisation at 121° and has a field of vision of over 180 degrees. The snap on both sides allows free adjustment of the size of the head circumference and is used together with a duckbill type mask for good anti-fogging effect. Inside can be fitted with myopic glasses with a 180 degree field of view. Conforms to EU certification standards. The lenses are individually replaceable.