Weldcote Metals 5050RC18X1SP Common Solder, Lead-Based, 50% Tin 50% Lead, Rosin Core, 0.125″ Dia. – Spool

With some exceptions, the tin/lead solders can be used to solder copper and most copper alloys, lead, nickel alloys and steel
Heat sources include soldering guns, irons and torch applications
Acid Core: For soldering materials with poor solderability, stainless steel application
Rosin Core: For electrical application
Tin/Antimony 95/5: Useful for applications where moderately elevated temperatures is a factor. It has a high electrical conductivity and high fluidity, recommended where lead contamination must be avoided; not recommended for use on brass or HVAC connections; CAUTION: Lead-bearing solders are not to be used in potable water systems