HCF/Pro-Grid Bulkhead and Diffuser O-Ring test-kit-type_Specialty This back-up ring goes inside

This back-up ring goes inside the tank and is used on filters manufactured after 3/03

Please note the wording is not 4 inches

The Wahoo cleaner comes preassembled and installs in minutes without any tools

no fraying

The Chemtrol PC5000 Filter/Pump controller is a fully programmable controller that features complete automatic control of water chemistry (ORP

HCF/Pro-Grid Bulkhead and Diffuser O-Ring test-kit-type_Specialty This back-up ring goes insideThis is a Hayward Diffuser O Ring replacement for HCF Series HCF7303C, SwimClear Cartridge Filters, and Pro Grid Vertical Grid DE Pool Filters. SX220Z2 is also a Bulkhead O Ring for Hayward MaxFlo VS Series pumps, MaxFlo XL, and MaxFlo II pumps.