This electrical solder is most commonly used in electronics. The 60/40 refers to the composition of the alloy, being 60 percent tin and 40% lead. This allows a lower melting point than 100 percent tin and will remain liquid for longer, allowing for better flow. The resin flux in the core cleans the surface of oils and contaminants, leaving virtually no residue.
This 500g solder comes on a plastic spool, however is also available in a storage tube of 15g (PES1615G) or a smaller plastic spool of 55g (PES1655G).