Forged double couplers are used to join two scaffolding tubes together at a 90 degree angle. They are made from forged steel, and the design allows for secure connections and superior strength. The double couplers are designed to be used with tubes of the same diameter, and they are available in different sizes to fit a range of different tube diameters. They are also available in both galvanized and ungalvanized versions, allowing for use in both indoor and outdoor applications.