Just a note for those of you that have the MSR Sweetwater Microfilter or are maybe still finding it in a store near you: I noticed on this website that it has been discontinued. I called MSR's customer service to inquire and was told it is true. They plan to keep producing replacement filters (as well as the optional siltstopper filters) for about 2 years, although that certainly is no guarantee. So if you are like me and this is your primary water filter, keep an eye on prices and inventory to make sure you have enough supply at home to meet your tripping needs when the replacement filters eventually disappear.. If you are in the market for a filter, go with something newer.