First line of defense for shielding strong static magnetic fields from magnets & speakers. Also for small transformers and motors. Strong magnetic fields are harder to shield because they tend to "saturate" the shielding material. This 4" wide sheet Iron alloy is a hefty .010" thick and has an exceptionally high magnetic saturation of 21400 Gauss and maximum permeability of 4000. Tin plated for excellent corrosion resistance and better conductivity, it can be soldered or painted.