The OMB-Series of replacement cartridges feature high quality carbon block media is manufactured from raw materials to precise specifications entirely at the Omnipure US manufacturing facility. Elements are finished with a single layer of spun-bonded polypropylene netting. Polypropylene end caps with compression gaskets are standard. Quality American made carbon blocks you can trust. Additional Details ------------------------------ Product description: The OMB-Series of replacement cartridges feature high quality carbon block media is manufactured from raw materials to precise specifications entirely at the Omnipure US manufacturing facility. Elements are finished with a single layer of spun-bonded polypropylene netting. Polypropylene end caps with compression gaskets are standard. Quality American made carbon blocks you can trust.