[Radio Wrangler]

They aren't Faraday cages, the metal is solid, so they also act on magnetic field components. Faraday screens are special, they are aligned grids of wires designed for purely electric field screening and are pretty much useless for general screening duties.

The idea behind the wire grids is that there is no path for circulating eddy currents.

This is a very common confusion, but it's wrong. You'll find real faraday screens inside some transformers to block capacitive coupling between windings.

These things are simple metal screening boxes, often plated steel or brass. They get soldered onto printed circuit boards over an area of componets doing something sensitive. Often the PCB has a groundplane area which acts as the lid, completing the screening box. They are a right pain for fault finding and access. They need a bigger soldering iron to remove them than they take to fit!

David