Braun Series 5 51B Foil & Cutter Replacement Head, Compatible With Waterflex Shaver Introducing the Braun Series 5 51B Foil & Cutter Replacement Head, designed for compatibility with the Waterflex shaver. As the world's #1 foil shaver brand, endorsed by the NFL, this replacement head ensures top-notch performance. Specifically tailored for Braun Series 5 (Waterflex) shavers, it should be replaced every eighteen months to maintain optimal performance. Replacing your shaver head can result in a 25% better shave, provided it is cleaned regularly for optimum performance. Keep your shaver performing at its best with this simple maintenance routine. World's # 1 Foil Shaver Brand, Based on global Braun value share in electric foil shaver market from May 2013 to to April 2014.Official Electric Shaver of the NFL.Fits Braun Series 5 (Waterflex).Shaver head should be replaced every eighteen months.Replacing your shaver head gives a 25% better shave. For optimum performance; clean regularly.