Is the marker official and likely to be maintained by the park staff? If it breaks or is stolen, is it likely to be replaced? That would make it ‘permanent’ in my opinion.
Park management is usually rough-and-ready, so most trail markers are going to be like this picture, or even simpler or cheaper (a painted spot or band of color).
I’ve had mixed results with trail markers, and most of what I’ve submitted has been rejected for one reason or another. My personal opinion is that they should be accepted so long as they are official. It can be hard to provide enough information for the community to verify, though.