GE SmartWater Filter Adapter - required when replacing MXRC, FXRC, FXRT, HXRT with MWF. The MWF filter + this adaptor can be used to replace thse old metal canister filters:Sears / Kenmore - 9905, 469905, 46-9905, 9905P, 04609905000.  Water by Culligan / GE SmartWater - FXRC, FXRT, MXRC, HXRT, WR97X10006If you are replacing a SmartWater cartridge with an adapter, it must be removed before installing the cartridge. To remove the adapter, turn it to the left about 1/4 turn. If you are replacing a Water by Culligan cartridge, leave the  adapter in place. This adapter will stay in the refrigerator when you replace future cartridges.NOTE: Use of this adaptor will add approximately 1" to the height of the installed filter.