Unicel builds the best-performing filter cartridge on the market. It all starts with quality components and more than 45 years of filter cartridge manufacturing. In 1985, Meissner Mfg. Co., Inc. introduced the UNICEL brand of filter elements as after-market replacements for the OEM products. Today, the UNICEL line is comprised of nearly 500 products that are manufactured in California with components sourced exclusively in the USA.