This page contains information regarding Star Trek: Discovery, and thus may contain spoilers.
The Mercantile drone was a type of small flying device used by the personnel of the Mercantile, a marketplace in Requiem, Hima, for various tasks in the 32nd century. A drone had three detached appendages surrounding a central body, which contained a camera. Drones were programmed with the ability of passing through force fields.
Tasks assigned to drones included the transporting of cargo, identifying couriers at the checkpoint located within the Mercantile's entrance, surveillance, announcing an individual was under arrest, and spraying a truth serum at a suspect during an interrogation.