These aftermarket refillable k-cup filters allow you to use your own coffee in k-cup pod style single serve brewers. Unlike the official version of the device where the top seals tightly and locks down, the aftermarket variations use a ‘flip-open’ top that does not lock. In fact, this model does not seal well or stay closed, something that gets worse over time. Even so, they work pretty well, and the machine holds them closed for the most part. Considering you can get several copies of this type for the price of one official unit, they are a viable solution when cost is a consideration, and do what you expect, but the design is not of the same quality.
Conclusion: Works, but could be improved.