There are many different Oral B toothbrush heads to choose from and the ones you need depend on the teeth you have. For example if you have very sensitive teeth then you need to get a very soft head so that any pain you feel will be reduced during brushing in the morning and evenings. This advice also goes if you have weak gums, it is well known that if you have weak gums then hard Oral B toothbrush heads can actually do some damage. If you are unsure of your particular situation then you need to see a qualified dentist for some advice.
Beware of buying Oral B products from eBay because this brand is highly replicated from sellers from China. This means that the toothbrushes you buy are actually of a much lower quality then you are led to believe. In the realms of marketing products this is actually illegal. Therefore you need to either buy from reputable sellers or stick to buying Oral B products from the local shopping mall. best carpet steam cleaner
Kids and adults actually need two different sizes especially if the kids are still having their teeth grown. Having kids use large and stiff brush heads is one sure way that leads to them having gum damage which is not what you really want. To avoid this it is good to get your local dentist to approve any dental products you use so you have the peace of mind that you are treating your teeth how they should be.