COMP Cams 8934-2 Retro-Fit Hydraulic Roller Lifter for Ford 352-428 FE and 429 460 Non-Roller Engines - Pair 0.875 inches diameter; 147 gram weight; 2.6 inches seat height Performance replacement for stock hydraulic roller lifters or retro-fit hydraulic roller lifters for non-roller blocks Decrease friction and increase longevity when directly compared to flat tappet lifters Accept much more aggressive cam profiles than flat tappet lifters will allow