24Megapixseal wrote:
https://www.focuscamera.com/photo/more-photo-video/cleaning-care/focus-5-piece-digital-camera-accessory-kit.html
Those cards are screen protectors! Evidently you use those scales on the sides to measure your rear LCD or even your phone screen, and then you probably cut to fit, peel and stick...
Let us know it this is correct... Try peeling back on edge... It's not just "a plastic card"
Odds are very high you are correct.