Rosin Core Solder is for electrical-electronic work, flux residue is non-corrosive and non-conductive.
Can be used on wiring in stereos, motors, appliances electronics and auto batteries.

60/40 Rosin Core Solder
60/40 solder is 60% tin - 40% lead

40/60 Rosin Core Solder
40/60 solder is 40% tin - 60% lead