Abstract: In a connector member for optical fibres, a fibre is coaxially held in a holder member which is supported by a silicone-rubber liner interposed between the bore of a housing and the circumference of the holder with the facility of radial adjustment in two mutually perpendicular directions by set screws making use of the compressibility of the liner. Longitudinal adjustment of the fibre is also provided by securing the fibre in a collet bush, in which it is held by a split collet, and which itself is longitudinally adjustable by a hollow coaxial set screw in a guide bore of an outer bush. An assembly jig is also described, in which a retractable tray of a wall supports the collet in front of an axial bore of a slide. This bore accommodates the collet bush, while a filament constituting the fibre is extended in the requisite position, in which it is located by V-grooves in end wall members of the jig.