We currently carry two KX Matrikx replacement water filters that are 5" x 2.5". Either of these two filters should work in your KX Matrikx System.
The KX Matrikx 01-250-125-050 Carbon Drinking Water Filter:
http://www.waterfilters.net/KX-Matri...r_p_0-404.html
The 01-250-125-050 KX Water Water Filter is a 0.6 Nominal Micron Filter and a 2 Absolute Micron Water Filter.
The KX Matrikx 02-250-125-050
http://www.waterfilters.net/KX-Matri...r_p_0-411.html
The 02-250-125-050 KX Water Filter is a 2 Nominal Micron Filter and a 5 Absolute Micron Water Filter.
Low water flow or water pressure is a great indicator that it is time to change you water filter. Typically when you water flow has decreased it means that your filter has become clogged with sediment and contaminants and needs to be replaced. It is often hard to give a definite time frame or gallons estimate on each specific water filter due to differences is water quality. Most filter do have an estimated time frame and/or gallons estimate, however, another effective way to tell is your water flow.