ScootsUSA 169-420-4508 GY6 Titanium Valve Spring Retainers Titanium Valve Spring Seat Retainer for 150cc and 125cc GY6 4-stroke QMI152/157 and QMJ152/157 engines and also also fits on 150cc GY6 4-stroke ZNEN engines commonly found in Bintelli, Gorilla Motor Works (GMW) and Puma scooters. These are made out of lightweight and high strength titanium. The light weight of the retainers reduces the strain caused by heavier stock steel valve spring retainers on your GY6 engine. The strong Titanium retainers also allow the springs to reach higher RPMs without the risk of breaking a retainer due to metal fatigue. Sold as a set of two, intake and exhaust pair. Set of 2Lightweight Titanium - Each Retainer is Approx. 3.5 Grams!Overall Outer Diameter: 20.6mm Inner Diameter: 7.2mm Overall Height: 8mm