Sunstar SS420MXR-L Works MX Size 420 Racing Chain with Masterlinks Sunstar is the largest O.E.M. supplier of sprockets and brake rotors in the world. In fact, your motorcycle probably came from the factory with a Sunstar sprocket. Need a reason to choose Sunstar? Every Sunstar product is imbued with superior quality, uses an exclusive heat-treatment and quenching process, is based on advanced research and design, and is sold at an added value price. This clip-style master link for the Sunstar 420 MXR1 chain makes for easy chain maintenance on your ride.