This is a standard shirt dangler ID that is seen in many season eight and nine episodes of The X-Files. It is confirmed as a late season dangler because of the colored FBI crest and barcode that is on the back side. This design detail was not introduced until later seasons.
This dangler also features an accurate holder. The curved top cutout detail matches confirmed screen used pieces. The holder is not screen used, but the card itself is.
Here’s the tricky part: I don’t know what production this was used in. In fact, I’m not even sure it was used in an episode of The X-Files. However, due to the circumstances under which I acquired this, I’m confident that it is screen used. It is also the exact same style as the ID’s used in the X-Files.
Perhaps an X-File should be opened to learn the origin of this very piece???