This Data Module can be seen in the "Winter Contingency" end cutscene as well as both "ONI: Sword Base" cutscenes. It's essentially a military grade flash drive, though I imagine its capacity is insane granted the game takes place in the 26th century. There are 3 parts to this model as it was built to house an actual flash drive,

seen here: http://www.amazon.com/Eaget-Metal-Flash-Memory-Storage/dp/B00U6ABC9C/ref=sr_1_3?ie=UTF8&qid=1440517453&sr=8-3&keywords=ring+flash+drive

The ring of the flash drive fits very snugly on the peg. The cap however is a bit loose. A slight modification to the slot may remedy this.

This was modeled and rendered in SolidWorks 2015.