A USB cable cover used when you install the XTouch screen mount from TeachingTech (found on Printables).
Designed to use the glass cover on a P1S or upgraded P1P to keep it restrained on the left side. So, you could use it on a bare P1P but the left side will be flapping in the breeze. But, on a bare P1P you could use some double sticky tape to hold it down and that should work fine.
Squeeze the end just a bit and it will snap right into the slot.