First we purchased an e7300.The timer did not work and the unit would turn itself off repeatedly.Called Sonicare who confirmed it did not work and I replaced it with an e5300.The timer did not work and the unit would turn itself off repeatedly.Called Sonicare who confirmed it did not work and I took it back for a refund this time.I suppose these are good toothbrushes. I've been using Sonicare for a bit over 10 years and never had any problems other than poor battery life. However, the above experience suggests they have some bad electronics or brush heads in the distribution pipeline.Or, now that Sonicare is owned by Phillips, quality has been compromised. It certainly was in the last razor I purchased.