Mouse droids performed simple tasks aboard starships and in military and corporate facilities. They beeped to themselves as they performed small repairs, delivered messages and guided visitors. occasionally exploding into panicked squeals when confused or frightened.
While attempting to steal the Quasar Fire-Class Cruiser-Carrier, the Ghost crew was double-crossed by members of the Free Ryloth Movement -- freedom fighters who preferred to outright destroy the ship. To stop them, rebels Sabine Wren and Zeb remote controlled an MSE droid -- with a charge attached -- toward the Twi’lek freedom fighters. Detonated at just the right second, the Rylothians were neutralized, and the MSE-series droid proved its worth once more.