In order to obtain a high output, it is necessary to turn the engine by high rotation. However, when using the engine in a high rotation region, valve jumping becomes easy to happen and the danger of breaking the engine increases. Therefore, it is required for tuned engines to make movement parts lighter. 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 an emphasis on both strength and weight in mind.