Horizontal rings fitted around the neck bin. neck struts: Eight thin, vertical struts on the exterior of the neck bin, between the top of the shoulders and the dome. dome: The rotatable top component of the travel machine. dome lights: Lights fixed to the dome, which flash when the Dalek is shown speaking. eye stalk: A rod projecting from the dome, which can pivot vertically. eye discs: A series of discs of varying diameter through which the eye stalk is threaded. eyeball: A spherical component fitted to the end of the eye stalk, shown in various episodes to contain the Dalek's visual apparatus. eye lens: A circular lens at the front of the eyeball which, depending on the variant, is sometimes illuminated or has a central pupil. dome cowl: A structure which projects from the front of the dome and surrounds the eye stalk pivot. ("New Series" Daleks only) General design Overview Externally Daleks have the appearance of a truncated cone varying between approximately 1.5 metres (5 feet) and 2 metres (6 feet 6 inches) tall depending upon the variant. They are equipped with a single mechanical rod-mounted eye which protrudes from a rotating dome, a directed energy weapon and a telescopic arm. Usually the arm is fitted with a manipulating device resembling a sink plunger. This item is shown in various episodes to be capable of holding people and objects, seemingly using a powerful vacuum. The weapon is depicted as having a variable output which can paralyse, stun or kill most life forms, disintegrate other Daleks and destroy buildings and spacecraft. Casing In Remembrance of the Daleks (1988) and the episodes "The Parting of the Ways" (2005) and "Doomsday" (2006) the Doctor states that Dalek casings are constructed from "bonded polycarbide", with this material being referred to as "dalekanium" in The Dalek Invasion of Earth (1964) and "Daleks in Manhattan" (2007). The casing is depicted as being impervious to most projectile and energy weapons, although not indestructible. In various episodes Daleks are shown being damaged or destroyed by overwhelming firepower, their own weaponry and falls from a height. In addition, in Revelation of the Daleks (1985), they are said to be vulnerable to "bastic-headed bullets". In appearances from 2005 onwards a Dalek's defensive capability has been shown to include an invisible force shield, with the eye remaining a weak point. The lower shell is covered with hemispherical protrusions. In