<p>The lamp has a base which consists of an electrically insulating injection-moulded plastic sleeve (110) and a holder (111) of the same material which supports the bulb (116). A metallic ring (121) surrounds the holder. Another metallic ring (122) embedded in the sleeve has four resilient welding tags (123) protruding into the interior (117) where they are brought to bear upon the inner ring (121). When adjustment is completed the two rings are welded together at the tags, using a tool introduced through a hole (124) opposite each tag.</p>
