ITEM NAME:63/37 1.0mm Tin Lead Rosin Core Solder Flux Soldering Welding Iron Wire Reel.1 Tin Lead Rosin Core Solder Wire. Material: 63% Tin 37% Lead. Easy to carry and it is sure an electronic enthusiasts essential gadget. We'd like to settle any problem in a friendly manner. We want to make sure you are happy with our item.