These clear glass lenses are 3mm thick with a scratch-resistant coating on both surfaces. They are shatterproof and offer 99.9% UV-protection. The style is in keeping with goggles dating from 1920, and were widely used in World War II partly due to the wide field of vision. The lenses are retained in a channel surround and located within the goggle frame and kept firmly in place by the headband clips. This allows you to remove and replace the lenses very easily.