This listing is for a Pack of 1 WRAS Approved A solder ring reducing coupling (also known as a or pre-soldered reducer) is a straight fitting used to connect two copper pipes of different diameters. Each socket features an internal groove pre-loaded with a precise amount of lead-free solder. To prepare copper pipe for solder ring fittings, cut it square, deburr the edges, clean the pipe end and fitting socket to bright metal with an abrasive pad, and apply a thin layer of flux before assembly. To solder a solder ring fitting, clean and flux the joint, assemble it, heat the copper evenly with a blowtorch until it reaches melting temperature, so capillary action draws the molten metal into the gap around the entire pipe.