Our Pentek 150233 - Metal Water Filter Housing Wrench will be the last wrench you ever need. If you have had trouble getting your housings loose during filter changes or if you have ever broken a plastic wrench, then you need our Galvanized water filter wrench. It will not bend, break, or bow. Inside Diameter (not from the tabs) - 6". Fits all Pentek #20 Big Blue housings. Not sure what size filter housing wrench you need? Find the correct one on our Choosing the Right Filter Housing Wrench page.