A service droid prototype was utilized by the Galactic Empire for maintenance tasks. The KX-series security droid's head was the origin for the droid's head's altered design. The service droid design is mirrored in the body construction of the custom-built pilot droid named L3-37.
The Greg Pak-written and Raffaele Ienco-illustrated Darth Vader (2020) 37 marked the initial appearance of the service droid prototype. Ienco has stated that the service droid shares a head design with a monster droid model, clarifying that it is a modified KX-series head. He inferred that the service droids also possess modified KX-series heads because of this shared head design.