10 Pack Toothbrush Heads for Burst

My wife and I share one Burst handle unit and we both use our own brush heads, so we remove one and swap it to the other one twice a day. We’d ordered these replacement heads once in the past and they worked all right, but this last batch is very defective. Six of the ten brush heads were very hard to attach onto the base, and the inside plastic collars broke off the first time we tried to remove them to swap them, as you can see in the picture. This made six of the ten brush heads completely useless. So basically, most of the brush heads are junk. As you can imagine, we won’t be ordering these again.