HyMu 800 alloy is a nickel-molybdenum-iron alloy capable of being heat treated to show very high initial permeabilities, maximum permeabilities and AC core losses at low magnetic flux densities. This alloy is produced in strip form at thicknesses less than 0.008" (0.02 mm). Cut lengths, heat treated to magnetic property requirements ready for photoetching, can be supplied. Coiled strip, suitable for blanking or forming, can also be produced.