This Manway Cover is designed for the HCF Series Filter. The HCF Series Filters feature an improved internal and external design that enhances performance and endurance. The filters distribute water more evenly with a multi-diffuser configuration, increasing filter cycles, effectiveness, and longevity of the filter. Installation and maintenance are easier than ever before. A transparent manway simplifies operation and the UV-protected and infusion molded fiberglass shell reduces corrosion and shields the unit from the elements, such as blooming and biofilm build up.