Culligan 144368 Metal Water Filter Housing Wrench is the best alternative to plastic wrench you will ever find. It is used as a housing wrench. Its filter diameter measures 4.5? which fits the Culligan 144368 filter housing and most #20 Big Blue housings. It is longer than a standard filter wrench with a rubberized handle for extra leverage. A directional arrow and the word ?loosen? are printed on the handle to prevent breaking the filter housing unit by turning the wrong direction. This galvanized water filter wrench will not bend or break and hence is a popular choice amongst customers.