A Diagnostics module was a tool used by Holowan Laboratories engineers which kept incomplete droids and other unfinished projects secured and locked in place. The diagnostics module used Durasteel bands to keep the subject in an erect position during initialization.

Sometime before 15 BBY, the Holowan Disaster was brought about by the failure of the diagnostics module to contain the new Assassin droid model IG-88.