Mu metal is a high-permeability magnetic shielding alloy used to redirect low-frequency magnetic fields around sensitive components. It is valued because it can reduce interference without needing active electronics, making it useful in legacy equipment such as televisions, recording gear, sensors, and test instruments.
In cyber security, mu metal matters because physical design can affect system integrity and reliability. If shielding is bent, removed, swapped, or poorly restored during repair or refurbishment, a device may become more susceptible to interference, signal drift, or degraded performance. That can complicate forensic work, safe reuse, and the operation of older systems that still support business or research functions. More broadly, mu metal shows that defense is not only software-based: physical materials can be part of the control plane for stability, confidentiality of signals, and predictable hardware behavior.