Specification: Model: ER4043 Diameter: 0.035" (0.9mm) Roll Weight: 1 Lb Quantity: 4 Rolls Material: Aluminum Description: ER4043, commonly referred to as “AlSi5", has a 5% silicon and is the oldest and one of the most widely used aluminum welding wires for general purpose applications. Less sensitive to weld cracking than other aluminum alloys and the 5% silicon content lowers the melting point, increases fluidity of the weld puddle and leaves a bright shiny weld deposit. ER4043 is commonly used for welding grades 6061, 6063, 5052, 3004, 3003 and cast alloys 356.0, 357.0, 413.0, and 443.0 to name just a few. .