We upgraded to this larger but MUCH more protective filter from the 3M Model A1 under sink filter in our 2011 Winnebago View 24K. This Aqua Pure C-CYST-FF Undersink Filter Replacement Cartridge is a direct fit replacement IF you have more room for this larger filter (MEASURE TWICE, ORDER ONCE). Our filter swap was as simple as twisting off the old A1 filter and twisting on the new one. We love that we're now protected from water born disease which is certainly possible with the poor quality of some of the campground water sources we've connected to. We first "pre-filter" with a Camco inline water filter at the water source connection to remove most solid contaminants... then again this larger cyst removing filter for our drinking / cooking water coming out of our kitchen sink.
Highly recommended vs. the non discontinued 3M Model A1 filter... IF you have the room for this larger filter.