The preferred wire diameter is governed by the welding current required for a particular application. The commonly used SA wire diameters lie in the range 2.0 to 6.0mm. Current ranges for solid wire are shown in the figure. Overlap in these ranges enables exploitation of wire diameter effects. For example, for a given welding current, small diameter wires give increased current density resulting in narrower and more deeply penetrating weld beads and increased metal deposition rates compared to a larger diameter wire. Arc starting and stability may also be improved with smaller wire diameters.