HIGHER QUALITY:Replacement Shaving Head & Cutter Blades with Hypo-Allergenic Foil Head with Bump Prevent Technology, Fit Model:Shaver Replacment Heads Compatible with Remington SPF-300 Replacement Screen and Cutter for Foil Shavers F4900, F5800, F7800 Shavers Easy to Install: You can replace the shaving heads in a few minutes.place a tiny drop of baby oil on each heads and allow shaver to run for 10 seconds after installation ,to ensure your shaver run properly and smoothly. Warm Tip:To keep Your Shavers Super Performance.We recommend that you replace shaving heads every 3-6 months