Lifespan well below expectations.

I have already tried two heads from the set and the result was disappointing in both cases.
• First head: After 30 days of use, the blue bristles had completely lost their color and the brush was already deformed. I continued to use it in case I was to blame due to improper use. After 40 days, it was no longer suitable for use — the bristles had splayed, bent, and were sticking out in all directions.
• Second head: Even worse. Discoloration after 20 days and complete deformation of the bristles after 35.
The photos clearly show the condition of both after 40 and 35 days respectively.
The expected lifespan of such a head is about three months, with the discoloration of the blue bristles serving as a replacement indicator. Here, we didn't even reach half of that — and we're not talking about simple fading, but total collapse of the bristles.
Normal use, twice a day, without excessive pressure, on an Oral-B iO electric toothbrush. Such wear in such a short period is unjustifiable.
If all the heads in the set behave like this, you actually get a supply for eight months, not two years — and the cost per head triples in real use. I do not recommend it.