I love this product. I was able to store my milk powder in each bottle, so saving space in the bag instead of having to carry a separate milk powder dispenser, and I could make a fresh milk bottle as and when i needed it. I was able to pour water into the milk bottle to the required level and then insert one of the powder dispenser inside the bottle too. I found that there were no leakage, and the powder stayed perfectly dry. I can put 6oz of milk powder... there is room for more I think, but not sure what the maximum it can hold. I purchased 3 sets of these, at 3 different suppliers, and I have found that the sizes are slightly different from each other which was a bit annoying. But apart from that, great product.