Our #19 steel water filter wrench will be the last wrench you ever need. It will not bend, break, or bow. Replaces the discontinued plastic 68892-31 wrench. Fits the Aqua-Pure APRO5000 system. Inside Diameter (not from the tabs) – 3.52″. Replaces Watts RO wrench. Not sure what size filter housing wrench you need? Find the correct one on our Choosing the Right Filter Housing Wrench page.