Renthal’s RR4 A highly specialized lightweight 520 sealed ring chain developed exclusively for Superbike racing applications where a combination of lightweight and durability are a must. Utilizes Renthal’s Self Regulating Seal (SRS) technology to increase service life. The specially developed Self Regulating Seal (SRS) ring is preloaded during assembly creating a spring effect. As the chain wears, conventional o-rings and x-rings loose their seal, however the SRS ring has the ability to unload itself during use keeping a tighter seal against the side plates. This offers increased longevity as the specially formulated grease remains trapped around the critical pin and bushing area longer while also keeping dirt, water and other contaminants out.