It contains 35%- 90% nickels. Higher is the nickel content higher is the permeability and lower is the magnetic saturation of the alloy. MN, CO, and Mo can also be added in trace quantities as impurity. Addition of small amount of other elements in Nickel – iron alloys improves their magnetic properties in certain direction. Thus CO reduces hysteresis, MN reduces coactivity and Mo increases permeability and reduces iron losses.