Whilst mu metal is available in many different gauges and indeed a single layer of mu metal is suitable for most commercial applications, optimal shielding results are obtained when a shield is constructed of multiple layers of mu metal.
In theory each layer should be of a light gauge and the shield constructed of many layers [...]

What is field attenuation?
This is also known as the shielding factor (S) and is a ratio of the magnetic field strength outside of the magnetic shield (Ha) and the resultant field on the inside of the shield ie Ha/Hi (no units) or S = 20 x log(Ha/Hi) (Db). There are various formula based on the [...]

Mumetal is one of a family of three Nickel-Iron alloys widely used to produce magnetic parts and shielding.
The three alloys concerned have the following approximate compositions and well known trade names:-
36%NiFe widely known as Supra 36, Nilomag36, Radiometal 36, Magnifer36
50%NiFe widely known as Supra 50, Nilomag 50, Radiometal 50, Magnifer 50
80%NiFe 5%Mo widely known as [...]

Mu Metal Mechanical properties at ambient temperature (reference guide)
Density: 8.7 [g/cm^3]
Youngs Modulus: 225 [GPa]
Poissons Ratio: 0.29

Specifications : ASTM A-753 Alloy 4, MIL N-14411C Composition. Mu metal is a 80 % Nickel, 4.5 % Molybdenum, balance Iron soft ferromagnetic alloy which means that it does not retain a field after the removal of an external magnetizing force. Mu-metal offers exceptionally high initial and maximum permeability with minimum hysteresis loss. It also has [...]

The most efficient magnetic shield shape is a spherical shield but this is difficult to manufacture in production terms. The next best is a cylinder with closed ends. The rounded surface of the cylinder is conductive to the absorption of magnetic flux. If the cylinder does not have end caps, the ratio of the length [...]

Most people are familiar with what a Magnetic Shield does, it simply stops or negates unwanted interference from magnetic fields. Not so many people are familiar with how it actually does it.
There are various types of ways and materials used in Magnetic Shielding depending on the frequency and strengths of the magnetic field.