These heads are of poor quality. They are only lasting a week, before needing to be changed. They start to wear on the second use. I purchased the same pack last year for my partner and his are great. I have compared my pack and his pack. The blue on his heads is darker, the brush part is firmer and lasts fo 2 to 3 months. That is why I am stating counterfeit in the title. Also the free pack of 4 I got with my toothbrush are the same counterfeit quality.