I bought these as I needed to prepare more than the three feeds that most other powder containers/dispensers allow without buying another space-consuming independent powder dispenser, and I also wanted the convenience of storing them in the bottle.
Overall I am very pleased with these dispensers. Initially I did have a couple of instances of formula powder going everywhere as the knack to fitting the lids can take a short while to master, though it did only take those two mishaps for me to grasp the knack of fitting them firmly but safely! (Much of the problem could have been down to sleep deprivation, though!!!) They fit very securely into the Tommee Tippee Closer to Nature bottles, and are an excellent solution for those who are looking to take their cooled, boiled water pre-measured into bottles along with the pre-measured formula without needing a completely independent formula dispenser and to save some space.
The down sides are that if you're short of steriliser space you need to carefully plan your sterilising to match the number of dispensers to the number of bottles, and ensuring your dispenser stays as sterile as possible whilst ensuring it's bone dry for the formula can also be a little difficult to master initially (especially if you use cold water sterilisation)!
I also can't see how you can fit the entire eight scoops of formula in to each dispenser as stated on the box, as mine are full to the brim at six scoops - and these aren't large scoops, they're just ordinary scoops of formula.
For those reasons I won't give these dispensers five stars, but they are definitely worth the four I've given them and I'd certainly recommend them!