The Pentek 154166 is the correct replacement for the following filter housings:
The Pentek 154166 Big Blue Filter Housing Cap is constructed of high-flow polypropylene (HFPP) with a 1" inlet/outlet port. Also known as part number 154166, the 1 1/4" internal port allows greater volume of water to pass through the cap more rapidly.
Pentek Big Blue Filter Housing Cap specifications:
The Pentek Big Blue Filter Housing Cap features a red pressure release button that can be used for bleed or optional pressure relief. The Pentek 154166 housing cap will not fit the Pentek #10 or #20 Big Clear Housings. Use the SW-3 wrench for #10 Big Blue Housing Sumps and the SW-4 wrench for the #20 Big Blue Housing Sump. To prevent cracking of the filter and water leakage, protect your housing system against freezing.