Uknown yellow label "detach.. Before.."

[EpicFail]

Hi everyone,

Some time ago I found a metal tag with some text on it. Was found on an American and German position, but probably American because it is English.

The right part of the label is unfortunately missing.
It says "Detach sa.. Before st..". There was also an iron piece attached to it, which will maybe help with the identification.
Does anyone know what this label was for? And what was it?

Any help is appreciated. Thanks in advance!

Lars