4 Coupling (Socket) Copper x Copper w/ StopThe 4" Copper Solder Joint Coupling (Socket) Copper x Copper with Rolled Up Tube Stop is a high quality plumbing fitting designed for securely joining two copper pipes in a straight line connection. The rolled up tube stop ensures proper pipe insertion depth for a strong, leak proof soldered joint. Made from durable copper, this coupling provides excellent corrosion resistance and is ideal for potable water, HVAC, and hydronic heating systems.