R3-3 SRS Road Chain The Renthals R3-3 chain has been specifically tailored for light to middleweight motorcycles. Lighter and less expensive than our R4 range, the R3-3 utilises the proven Renthals SRS technology for increased service life. Nitrile Self Regulating Seals (SRS) retain a special vacuum injected grease around the critical pin and bush area, which extends the life of the chain.