Small bottle of silicone lubricant. Used to keep the face of the eye port trim flexible and better able to seal against the shield and allow the shield to open and close more easily while maintaining a good seal. Re-application of lubricant is only necessary when the shield becomes difficult to open or close, or the shield will not fully seal and allows air to pass the gasket. Only a tiny drop spread thinly around the entire face of the gasket is all that is needed - do not over apply. The bottle is tiny, and only half full, as very little is needed. *The quarter is for size reference and does not come with the bottle.