Review (4/5): Best replacement brand so far
I have written another review for a different company of this same model replacement head toothbrush with attached video. Long review short, these are much better. The bristles are barely more firm, but that is good, I actually feel like my teeth are being brushed. The heads fit correctly and don't make excessive noise. I have not seen a 1-2 bad replacement heads per 6-pack. I do feel they last the full 12 weeks.
If you require this model replacement head then this is what you want. Better packaging, better heads and a nice chunk of money is saved on these rather than buying the name brand found on your batter/handle.