Kester “”44″” 60/40 Solder Rosin “”44″” Is A High Activity Ra Core Flux Designed For Excellent Instant Wetting Action, Even On Nickel Surfaces. Although “”44″” Is A Ra-Based Material, The Residues Are Non-Corrosive If Not Cleaned. Per J-Std-004, “”44″” Is Classified As Rom1 Flux.• Type: Wire• Alloy: 60/40 (60% Tin, 40% Lead)• Description/Function: Wire Solder• Diameter: 0.031″ (1.57 Mm)• Core Size: 66• Contains Lead: Yes• Package Type: Spool• Weight: 1 Lb Also Available In Diameter Size 0.062″”.