Hobart SDX S3Si-EH12K description: SDX S3Si-EH12K is a copper-coated, carbon-steel solid wire for submerged arc welding. SDX S3Si-EH12K has a high manganese and low residual content for enhanced mechanical properties desirable in critical applications. Hobart recommends using this wire with the following flux(es): SWX 110, SWX 120, SWX 130, SWX 135, SWX 140, and SWX 150.