Adafruit Solder Wire - 60/40 Rosin Core - 0.5mm/0.02" diameter - 50 grams
This spool of solder contains approximately 0.6mm / .02" diameter in standard 60/40 formulation. This is not lead-free solder, so not for lead-free/RoHS shops. However, for kit builders its a joy to use, much easier than lead-free and great for beginners. For flux, it contains a 'no clean' rosin core. This diameter solder is best for any SMT/fine-pitch work as it allows you to deposit small amounts of solder.
This is "60/40" leaded solder with 40% Pb (Lead), 59.5% Sn (Tin) and trace Ag (Silver) %0.015, Cu (Copper) %0.04. Sometimes this is referred to as [59.5/0.015/0.04]