Embryos which evidenced any minor defect were segregated and subjected to genetic engineering that limited their brain functions and enhanced their loyalty to the Dalek race. They were housed in special Construction Casings which were smaller and slighter than regular Travel Machines. These casings did not feature the usual weapon and manipulator arm combination; rather they possessed a range of tool and grappling arms which were used in the manufacture and demolition of technology across the Dalek Empire.
While there were untold millions of these drones throughout Dalek space, it was extremely rare for a non-Dalek to see one and survive. To those outside the Empire, it appeared that slaves and robot workers performed every menial and tough, labour intensive task – Daleks did not. The intelligence of these drones was reduced such that they could perform the tasks to which they were assigned with a degree of initiative, but nothing else. To all intents and purposes they became as robot workers, having their memories wiped and reprogrammed on a regular basis. Only their initiative set them above the automaton workers also utilised by the Dalek race. The workers had embedded self-termination protocols and it was not unknown for the Dalek leadership of a planet to simply terminate them rather than spend the time to load the drones back on the ships before leaving a region.
