Rudimentary Medium Credit Case

Rudimentary Medium Credit Case is a premium class 1 lockbox. Upon use, these boxes award credit 308.

Source
Rudimentary Medium Credit Cases can be obtained through the Crew Skill Slicing. They can be harvested from Security Footlockers on Balmorra (Empire) and Taris (Republic), which requires level 90 Slicing, or from level 10-16 Slicing missions.