Renthal s R4 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.SRS ring technology enhances chain flexibility and offers smoother operation than standard o-ring chains.High alloy steel plates and pins, solid bushings and rollers, shot peened side plates for added strength and gold side platesFeatures a solid pin rivet providing additional strength for riveted seal.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 lose their seal, however the SRS ring has the ability to unload itself during use keeping a tighter seal against the side plates.