Vortex Racing EK 420 SRX Clip Master QX-Ring Semi Press 130 Links- GoldThe EK SRX Series Chains are equipped with QX rings, surpassing traditional O ring chains in performance. Laboratory tests demonstrate that QX rings reduce friction by 40 percent, extending chain lifespan by up to 50 percent. Each chain link is designed with weight saving holes, maintaining strength while minimizing rotating mass. These features combine to maximize rear wheel horsepower delivery and enhance throttle response.