The OMB-Series of replacement cartridges feature the new Omnipure Block™ media. This high quality carbon block media is manufactured from raw materials to precise specifications. Filter elements are available in 10 micron, 5 micron, 1 micron, .5 micron, and 1 micron lead reduction formulations. The OMB-Series is designed to fit in standard 9 ¾' (10") and 20' cartridge housings.