Quality filter housings do a great job of keeping water leaks at bay, but they can be very difficult to unscrew when it's time to install a new filter. The Pentek-SW-4 filter wrench will save you from the hassle of wrestling with a stuck filter housing and pick up a wrench that fits your housing perfectly. The Pentek Filter Wrench fits Pentek Big Blue filter housings. Perfect for loosening a stuck filter housing. Made in U.S.A.