Overview of the variety of Philips Sonicare model names
Does anyone know an overview of the Philips Sonicare models? I find it very confusing and can't get my head round it. What is the difference between the various series such as 3000, 4000, 5000, 6000, 7000 and 9000? I realise that presumably the higher the number, the more "features" a model has. There is also a variety of models within the series, such as 5100, 5300, etc.
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