An adjustment mechanism comprising: (a) a lower pultrusion; (b) an upper pultrusion; and (c) a plurality of cam blocks located between the lower pultrusion and the upper pultrusion; wherein the plurality of cam blocks are longitudinally movable relative to the lower pultrusion and the upper pultrusion so that as the plurality of cam blocks longitudinally move, at least a portion of the upper pultrusion moves away and/or angularly relative to the lower pultrusion.