Part # 90-423-3120
I think this might be what is very old and stretched out of place. Does this fit inside the cartridge like a washer?
Hi Vanessa, The Kit 231 is a complete set of O-Rings for the Jacuzzi CFR Cartridge Filter. The O-Ring will act as a seal to prohibit anything from passing through. If your lid/cover O-Ring is stretched out you may replace it with PART# 4666-05.