Abstract: A penetrable flexible strip closure for covering an opening includes an extrusion secured across the upper end of the opening as a header. The extrusion provides a continuous open ended T slot and individual clamps for each strip extend through generally central openings in the strips, which overlap at their side edges, and have enlarged heads received in the enlarged portions of the T slots. Releasable securing members are provided on the shanks of the clamps, which extend out the reduced size slot portions of the T slot, to clamp the lapped upper ends of the flexible strips against a bearing portion provided on the extrusion.