The ultimate in comfort for prescription glass wearers. Flexible PVC frame fits comfortably over most prescription glasses while the 1 ½" wide elastic headband goes over the outside of the helmet. The 504 is designed to fit inside of most standard helmet openings yet seal completely to the face utilizing a Super Seer's exclusive lever action strap bracket and thick comfortable face foam. Prescription glass "bow relief's" is built in standard to alleviate pressure points. Large foam ventilation area affords sufficient airflow to minimize fogging.