I have been using the brush heads for about 2 weeks now in combination with the Philips Sonicare 9900 prestige.
And I am really very satisfied.
The brush is not too hard, but not too soft either.
And I really notice that my teeth are whiter now.
And plaque is also already reduced.
I used to suffer from irritated or damaged gums, since using this I have not had this cog.
I also think the notification of how long your brush can last (via the app) or when you need to replace it is definitely a plus.
Because honestly, I used to not keep up with this.
And then I probably used my brush too long.
So, general conclusion:
Very satisfied. And definitely recommended.