a polarized screw base assuring constant angular orientation of a lamp has a polarizing locator for engaging a stop in a mating socket . the locator consists of a length of metal rod welded lengthwise on the crest of a base thread with multiple spot welds to assure adequate shear strength . the leading end of the locator is formed with a hooked or alternatively with a balled end to achieve a locking effect with the stop in the socket .