I purchased three cartridges with bottles and teats. The cartridges are very handy and useful, especially when you’re out. You can easily add formula to water with just a quick twist, and it dissolves perfectly without any lumps.
However, the downside is that the cartridges can’t be placed in a sterilizer. They must be washed and cleaned in hot water, which I find inconvenient, as I prefer to fully sterilize anything used for an infant.