Abstract: The housing, which is of circular cross section, defines a series of spaced, terminal-receiving cavities arranged in a ring about the axis of the housing. An annular terminal retainer is received in an annular recess in the housing, at the outer periphery of a ring of terminal cavities. The retainer is provided with radially inwardly projecting terminal retaining members. The retainer ring can be moved between a first position, in which the terminal-retaining members are clear of the cavities, to allow terminals to be inserted into the cavities and a second angular position in which each retaining member intersects a respective cavity to overlie a collar on the respective terminal therein so that it is locked in its cavity.