General Tools & Instruments 154ST Swaging Tool Set
Swaging tools are pounded into the end of copper tubing thereby allowing the next piece of tubing to be fitted into it.  This eliminates fittings and reduces solder joints.  This swaging tool set is made of treated alloy steel, plated to prevent rust.  It comes in set of 4 swaging tools with specs of 1/4", 3/8", 1/2", and 5/8".