This applies to the following models only.P210R, P300R, M200, M300 Cartridge How to Replace Cartridge Cartridge Replacement (30-Sec) Cartridge Replacement (2inch/3inch) Step.1 Please open the bottom cartridge door of the device. Step.2 Align the cartridge with the shape of the slot. Step.3 Push it in until you hear a click. (See the engraved "Push Here" mark for reference.) Step.4 Please close the cartridge door cover well. Confirm