This is the first Maps of Mastery product that provides an empty floor grid for building new encounters from scratch.
What the description above doesn't tell you is that the Railway Floor lines up with each of my "Mass Transit" posters and the newly revised Railway Station Tiles, allowing you to expand the railway system that runs through all of those products. The sheets of terrain in Deck Space can expand the same maps even further.
Also important to note, since others have raised comparisons in the past: this poster covers a larger area than Paizo's flip mats, but it is not laminated. I do suggest getting this poster laminated if you have the means: the Cargo Bay Floor in particular would be great for drawing out your own maps with dry erase markers.