We have upgraded the Ceramikx again to the Doulton Ultracarb OBE. (made in England). This new model has a larger diameter at 2 3/4 inch for a much larger surface area. These will still fit our standard size housings. The Ultracarb is rated at 2 liters per minute flow and is suitable for all water sources including town water supply as it is Chlorine and Heavy Metal rated. If you are on an untreated water supply and do not use a Sterilight UV system we strongly recommend the use of this top quality Ceramic cartridge as a minimum for ULTRA Safe drinking water. Suitable for 10" STD size housings. E-Coli, Cholera, Shigella, Salmonella, Klebsiella, Cysts, Giadia, Chlorine, Heavy Metals, Taste and Odor. Please note we still recommend that this filter cartridge has a minimum of 40 PSI water pressure and must have a 1 micron prefilter to protect it from sediment prematurely blocking it.