New in factory plastic as seen in photos..A47.. 5% magnesium aluminum (AlMg5) filler metal welding wire for MIG welding process..With better corrosion resistance when exposed to salt water and higher shear strength due to additions of magnesium..ER5356 should be used for welding 5000 series aluminum base metals, 5050, 5052, 5083, 5356, 5454 and 5456.