Magnetic saturation is the state reached when an increase in applied external magnetic field cannot increase the magnetization of the material further, so the total magnetic flux density more or less levels off. (Though, magnetization continues to increase very slowly with the field due to paramagnetism.) Saturation is a characteristic of ferromagnetic and ferromagnetic materials, such as iron, nickel, cobalt and their alloys. Different ferromagnetic materials have different saturation levels.