Auto-destruct sequencer

From Memory Alpha, the free Star Trek reference

An auto-destruct sequencer is a device aboard Romulan starships used to engage auto-destruct.

Admiral Alidar Jarok's Romulan scout ship was equipped with an auto-destruct sequencer and when he left his ship to beam aboard the USS Enterprise-D, he set the sequencer to make sure that the technology wouldn't fall into Federation hands. (TNG: "The Defector")