Manipulator arm

The manipulator arm is the large mechanical arm usually found on most Dalek models, the exeptions being some Dalek Emperors' models and the Special Weapons Dalek-type model.

It is usually found in the right-hand socket in the Dalek mid-section, with the gunstick on the left.

Plunger
Manipulator arms typically have a shape like a plunger. For this reason, Dalek technology often has circular controls with which some an arm can interface by moving clockwise or anti-clockwise. However, the black tip at the end, which gives the arm its "plunger" shape can change into different shapes if needed (such as finding the combination of electronically locked doors). (DW: Dalek)

Even the Dalek dies, its arm can still operate machinery if used by a live person (DW: Remembrance of the Daleks). The arm can optionally can have a telescopic feature to enable the arm to extend outward. (DW: The Dalek Invasion of Earth)

It could also serve as a weapon. Placed over the nose and mouth, the arm can generate enough hydraulic suction to suffocate and kill a Human and enough to traction to more than crush a human skull or rip through sheet metal. (DW: Dalek, TDA: I Am a Dalek). It could also extract information from brainwaves. (DW: Dalek, Doomsday)


 * The brainwave extraction ability has only been known to have been exhibited by the post-Time War Cult of Skaro, so it is not known whether pre-Time War Daleks, or even post-Time War Daleks not in the Cult of Skaro, could extract brainwaves via manipulator arm or do many of the other abilities exhibited by the Cult. It is also unknown whether the shape-shifting technology of the plunger tip is also limited to post-Time War Daleks.

Claw
Alternatively, the arm can terminate in a simple mechanical claw with two pincers.