The Iron Box: a magical device

[Feywer96]

I remember hearing or reading somewhere about a "device" used in a magical context: an iron box.

If I am not mistaken, what ever is placed within the container is hindered from "effecting anything outside of it" - like if you were to put a cursed item into the box then the iron would render it ineffective and "neutralize" it.

And although this may sound similar to the "black box" used to put sigils in and 'torment' ('constrain and compel') the spirit in question during evocations, these are not the same.

The belief that iron has magical properties to keep away or ward off evil or negative forces goes way back. And interestingly, was even a desired choice for doing curses and the lot, such as the iron tablets discovered in ancient rome.

Any thoughts or additions about this device?