The ZFM cartridge is a standard DSE-901 Cartridge that has had the filler removed. In its place is a stainless steel screen custom fit to the shape of the cartridge. The surface resistance of the liquid keeps it from flowing out through the screen, the same way as it did when suspended in the filling. This mod removes the fowl taste associated with a cartridge running low.

Since there is no filling in the cartridge there is more room for liquid. A completely dry cartridge should hold 19-20 drops. Another benefit to removing the filling is that it is now possible to run a cartridge down to almost completely dry, saving you from waisted liquid trapped in filling but not exposed to the heating element.