Eyelet of gaskets are additional reinforcement place on edge to decrease penetrating gasket material by media and increase chemical resistance of connection. Eyelet can also provide good safety barrier from erosion of abrasive media. But eyelet not increase extremely resistant for temperature and internal pressure which should be analysed additionally. 

Additionally eyelets (outer cover) can be applied on external diameter – this way of cover is useful for provide barrier for oxygen from air to prevent or decrease oxidize of expanded graphite in temperatures over 450 deg. This can be very useful for exhaust gas applications. Without oxygen in ideal conditionals graphite can reach 2000 deg… so it can bring good effect for steamline gaskets made from reinforced graphite gasket.