The GE Merlin 1266690 is a 10 Micron Sediment Prefilter for the GE Merlin Reverse Osmosis System. This filter is optional and not required for the GE Merlin Tankless RO System.The GE Merlin sediment water filter protects and extends the life of the GE Merlin Reverse Osmosis Membrane by reducing sediment before it reaches the RO Membrane.The GE Merlin 1266690 water filter reduces sediment. rust. sand. and dirt from your water. It does not filter chlorine taste and odor like the GE 3038333 Carbon pre-filter. The GE Merlin Carbon 3038333 pre-filter must be used before the GE Merlin RO Membrane 3038333 if your water contains chlorine.The GE Merlin 1266690 Sediment Water Filter should be changed approximately every 6 months.