|A Mu Metal Enclosure|
Mu metal is an alloy which is known for its high permeability. It is composed of nickel(77%), Iron(16%), Copper(5%), and Chromium (2%). Its relative permeability is between 80,000 and 100,000. It has low hysteresis losses when used in AC circuits. Mu metal is also more malleable which makes it easier to make into thin sheets.
The name Mu comes from the Greek Alphabet Mu which is the symbol for permeability.