When you can fit the element gauge around the filter of your MSR WaterWorks EX or MiniWorks EX, it's time to replace the filter with the MSR Marathon EX Ceramic Element. This ceramic element removes protozoa and bacteria down to . 3 microns, including giardia and cryptosporidium. If you have an older MiniWorks or WaterWorks, not to worry--this MSR element not only works with them, but it also increases flow rate by 25%.