Fitment：For Predator 420cc Fo GX240 GX270 GX270 GX340 GX390 Engine. This is for a set of dual valve springs (a total of 4 separate springs). Approximately 65lb at 1.125 installed height, 60lb at 1.2 with 140lb open pressure (. 375 lift). These valve springs are designed to provide a higher spring rate than standard valve springs, which helps to prevent valve float even at extremely high RPMs. The dual spring design provides additional support and helps to maintain consistent valve timing and lift, improving engine performance. These valve springs are made from high-quality materials that are strong and durable, ensuring long-lasting performance. Stainless steel valves and billet or titanium retainers are required. Valve spring pockets may need to be modified.