The regular brush head that my EasyClean Sonicare came with seemed to irritate my gums; the brush was so big it was hard to keep it just on my teeth. The smaller size head makes way more sense to me & I'm not even a small person with small teeth; I'm 6'2"(!) Brushing the back face of my teeth is now done with precision & ease; & my gums (at the rear back) are thanking me everyday for making this purchase. The only drawback is that it takes longer to brush all my teeth, but really I don't mind that it takes an extra minute; it's woth it.
These are toothbrush replacements... enough said... Good thing is they're cheaper than the ones you get from retail... if you can find it in retail. Buy when needed, because I got two pairs of these sitting on the shelf right now and the ones that come from with the toothbrush are still working very well.