In order to obtain a high output, it is necessary to turn engine by high rotation. However, when using engine in a high rotation region, valve jumping becomes easy to happen and the danger of engine breakage increases. Therefore, it is required for tuned engine to make a movement part light. The role of a retainer is a stopper for valve springs, retainer needs to be extremely strong and lightweight for reliability and engine response. The JUN Titanium Valve Retainer has been developed with emphasis on both strength and weight in mind.