Produsentens info:     Genuine Mini Spares part- 1.5 Hi Lift Roller-tip rocker assembly for 1275cc with gold anodised steel posts. These extra high-spec alloy Purple rockers were introduced in 1998 to give push rods a better clearance on A Plus heads. Pre 1998 blue type pre are not interchangeable. Our material spec is higher and therefore more expensive than many others available on the market. The alloy rockers have hard centreless ground roller tips and PB1 phosphor bronze material bushes on a competition thick-wall Mini shaft,with nuts and EN8 adjuster screws. Ensure you tighten down all posts equally to eliminate stress fractures on shaft if used on small bore heads (not advised)it is necessary to re-arrange the rockers to line up the tips with valve stems. The ultimate lightweight alloy valve gear giving maximum efficiency cutting down side loading on valve stem, reducing friction and wear whilst increasing rigidity. The 1.5 hi-lift keeps valves open approximately 20% more at any given point, although opening and closing periods remain the same, and vastly improves volumetric efficiency and, therefore, power output. These combine in a high quality yet economical roller rocker set, as the roller tip is the most important factor to reduce valve and guide wear when using modern performance cams.