Adjustable headband

Claim 1

AN ADJUSTABLE HEADBAND COMPRISING A STIFF FLEXIBLE NON-METALIC STRIP OF SUBSTANTIALLY CONSTANT THICKNESS AND HAVING OVERLAPPING END PORTIONS, SAID END PORTIONS BEING FORMED WITH SUBSTANTIALLY STRAIGHT LONGITUDINAL EDGES IN SPACED GENERALLY FACING RELATION WITH EACH OTHER AND EACH END PORTION BEING FORMED WITH RECESSES ON OPPOSITE FACES IN THE REGION ADJACENT TO AND OPENING THROUGH THE RESPECTIVE LOINGITUDINAL EDGE, GUIDE MEANS SLIDABLY RECEIVING SAID END PORTIONS AND CONSTRAINING THE LATTER TO RELATIVE LONGITUDINAL MOVEMENT, A SUBSTANTAILLY STRAIGHT METALLIC TOOTHED RACK EXTENDING ALONG AND IN ENGAGEMENT WITH EACH OF SAID LONGITUDINAL EDGES WITH THE TEETH OF THE OTHER EXTENDING TOWARD AND SPACED FROM THE TEETH OF THE OTHER RACK, EACH OF SAID RACKS HAVING A THICKNESS APPROXIMATELY EQUAL TO THAT OF THE ADJACENT END PORTION AND HAVING ITS SIDES SUBSTANTIALLY FLUSH WITH THE ADJACENT END-PORTION FACES, A PAIR OF INTEGRAL METALLIC EXTENSIONS ON EACH OF SAID RACKS EXTENDING CONFORMABLY INTO THE ADJACENT RECESSES FOR FIXED EMBRACING ENGAGEMENT WITH THE ADJACENT END PORTION, EACH OF SAID METALLIC EXTENSIONS SUBSTANTIALLY COMPLETELY FILLING A RESPECTIVE RECESS AND BEING SUBSTANTIALLY FLUSH WITH THE ADJACENT SIDE OF THE ASSOCIATED RACK AND ADJACENT END-PORTION FACE, FOR FIXED SECUREMENT OF EACH RACK TO ITS RESPECTIVE END PORTION WITHOUT PROJECTION BEYOND THE END-PORTION FACES FOR UNOBSTRUCTED RELATIVE LONGITUDINAL MOVEMENT OF THE END PORTIONS, AND A GEAR ELEMENT ROTATABLY MOUNTED IN SAID GUIDE MEANS AND IN MESHING ENGAGEMENT WITH BOTH OF SAID RACKS, FOR EFFECTING RELATIVE LONGITUDINAL MOVEMENT OF SAID STRIP END PORTIONS.