It includes SCP 023, 131, and 173, the blink mechanic (press ‘b’ to trigger a blink), and the Class-D Uniform and personelle. Also includes the Document Crafter (functional!) and three pearls and documents for the above SCPs (nonfunctional).
This mod adds a number of creatures, artifacts, and locations from the SCP-Foundation’s wiki: http://www.scp-wiki.net/, most popularly SCP-173 (Don’t Blink! Also includes a blink mechanic.