This is the second pack of renewal that I purchase 4 brushes. Always satisfied with the product. After a year of experience, at 2 brushings per day of approximately 3-4 minutes, I notice that I change the brush on average every 2 months (sometimes less). Philips announces on average every 3 months. 25 pack, this comes back to me on average about ten cents a day to have a consistently effective brushing. No complaints. I had considered buying a pack of generic brushes, but the comments customers have alerted me to the fact that the results are far from the expected height. So I stay like this and welcome the teeth clean and smooth! Bravo ...