The average Braun shaver cuts 6 million hairs every 18 months. This means the head will gradually wear out and your shave can become less close and comfortable. That's why Braun recommends changing your shaver's foil & cutter block every 18 months to get your shaver back to its best. Take care of your shaver, and it will take care of you. Box includes: 1 X Series 9 Pro Shaver Head Replacement, Silver