It looks like the place I get my water filters from had a mis-pick at their warehouse. Received cartridges that probably fit my filter heads, but they're smaller and do entirely different things to the water so hopefully they can figure out a way to take the wrong filters back and send what I ordered. I have a couple slower filters that do comparable things with the water chemistry that I can swap if that takes too long so it's not an emergency, just an annoyance.