6 months, I notice that I actually collection of AVENT Natural: of the latter, small format that fits in all bags, which can take you anywhere and which are used for water, those 260 ml + a large 330 ml very convenient for the amount of milk for breakfast. After the number is adapted (debit) nipple to age.
The rings, teats and lids are compatible and interchangeable from one bottle to another in the same range 'Natural'.
They are not compatible with range AVENT 'Classic'.