The American Plumber SW-3 fits the following #10 Big Blue Housings with 1 inch and 1 1/2 inch Inlet and Outlets:
The American Plumber WWHD or SW-3 Filter Spanner Wrench is approximately 5.875 inches wide (inside diameter). This sump wrench is designed to loosen the bottom of the filter housing during cartridge replacement (PLEASE NOTE: The wrench should NOT be used to tighten the housing). Part number 150296.
The American Plumber SW-3 specifications: