Cleat materials

Claim 1

A JOINT FOR JOINING ENDS OF SEPARATE AIR DUCTS, WHICH JOINT COMPRISES A FIRST SUPPORTED AIR DUCT HAVING TOP AND BOTTOM WALLS WITH END EDGES; A SECOND AIR DUCT HAVING TOP AND BOTTOM WALLS WITH UNSUPPORTED ENDS; FIRST CLEAT MEANS JOINING THE END OF THE SECOND DUCT TOP WALL TO THE END OF THE FIRST DUCT TOP WALL; AND SECOND CLEAT MEANS JOINING THE END OF THE SECOND DUCT BOTTOM WALL TO THE END OF THE FIRST DUCT BOTTOM WALL; EACH OF SAID CLEAT MEANS BEING A REVERSIBLE CLEAT AND COMPRISING: A FIRST GENERALLY PLANAR SHEET-LIKE CLEAT SECTION HAVING FIRST AND SECOND SURFACES AND FIRST AND SECOND EDGES, A SECOND GENERALLY PLANAR SHEET-LIKE CLEAT SECTION HAVING FIRST AND SECOND SURFACES AND FIRST AND SECOND EDGES, SAID SECOND SECTION BEING GENERALLY PARALLEL TO SAID FIRST SECTION AND HAVING ITS FIRST SURFACE CLOSELY FACING THE SECOND SURFACE OF SAID FIRST SECTION, A THIRD GENERALLY PLANAR SHEET-LIKE CLEAT SECTION HAVING FIRST AND SECOND EDGES, SAID THIRD SECTION BEING GENERALLY PARALLEL TO SAID FIRST AND SECOND SECTIONS AND HAVING A SURFACE CLOSELY FACING THE SECOND SURFACE OF SAID SECOND SECTION, A FIRST INTEGRAL SHEET PORTION DEFINING AN OUTWARDLY PROJECTING INTEGRAL RIB ALONG THE FIRST EDGE OF SAID FIRST SECTION GENERALLY PERPENDICULAR TO THE FIRST SURFACE OF SAID FIRST SECTION, A DOUBLE-THICKNESS INTEGRAL SHEET PORTION COMPRISING AN OUTWARDLY PROJECTING INTEGRAL EXTENSION OF SAID FIRST SECTION FROM ALONG THE SECOND EDGE OF SAID FIRST SECTION, SAID EXTENSION BEING FOLDED OVER UPON ITSELF AND EXTENDING DOWNWARD TO A POSITION BELOW THE SECOND EDGE OF SAID FIRST SECTION AND ENCLOSING THE SECOND EDGE OF SAID FIRST SECTION AND MERGING WITH THE SECOND EDGE OF SAID SECOND SECTION, SAID EXTENSION BEING GENERALLY PERPENDICULAR TO SAID FIRST SECTION, SAID RIB AND EXTENSION BEING SPACED FROM EACH OTHER AND GENERALLY PARALLEL TO EACH OTHER AND DEFINING AN INVERTED CHANNEL TOGETHER WITH SAID FIRST CLEAT SECTION, AND A JOINING PORTION JOINING THE FIRST EDGE OF SAID SECOND CLEAT SECTION WITH THE FIRST EDGE OF SAID THIRD CLEAT SECTION, SAID JOINING PORTION COMPRISING AN INTEGRAL SHEET PORTION EXTENDING IN AN ARC OF ABOUT 180 DEGREES TO DEFINE A FOLD MERGING WITH THE FIRST EDGES OF THE SECOND AND THIRD CLEAT SECTIONS, SAID FIRST AND SECOND AND SAID SECOND AND THIRD CLEAT SECTIONS CLOSELY FACING EACH OTHER TO TIGHTLY RECEIVE THE WALL ENDS OF OPPOSITE ONES OF SAID DUCTS, THE FIRST EDGE OF SAID FIRST SECTION AND FIRST EDGE OF SAID SECOND SECTION COMPRISING A PAIR OF LIPS DEFINING A FIRST ELONGATED SLIT-LIKE OPENING FOR INSERTION OF THE END WALL OF A DUCT, THE SECOND EDGE OF SAID SECOND SECTION AND A SECOND EDGE OF SAID THIRD SECTION COMPRISING A PAIR OF LIPS DEFINING A SECOND ELONGATED SLIT-LIKE OPENING; THE TOP WALL OF SAID FIRST DUCT HAVING ITS END PORTION WITHIN SAID SECOND OPENING AND TIGHTLY BETWEEN SAID SECOND AND THIRD PLANAR SECTIONS OF THE FIRST CLEAT MEANS, THE TOP WALL OF SAID SECOND DUCT HAVING ITS END PORTION OVERLYING THE END PORTION OF THE FIRST DUCT TOP WALL AND RECEIVED WITHIN SAID FIRST OPENING AND TIGHTLY BETWEEN SAID FIRST AND SECOND PLANAR SECTIONS OF SAID FIRST CLEAT MEANS, SAID FIRST DUCT HAVING ITS BOTTOM WALL END WITHIN THE FIRST OPENING AND TIGHTLY HELD BETWEEN THE FIRST AND SECOND PLANAR SECTIONS OF SAID SECOND CLEAT MEANS, AND SAID SECOND DUCT HAVING ITS BOTTOM WALL END PORTION OVERLYING AND OVERLAPPING THE FIRST DUCT BOTTOM WALL END PORTION AND RECEIVED WITHIN THE SECOND OPENING AND TIGHTLY BETWEEN SAID SECOND AND THIRD PLANAR SECTIONS OF SAID SECOND CLEAT MEANS; AND MEANS IMPALING EACH OF SAID CLEATS AND THE WALL ENDS RECEIVED THEREBY AND HOLDING THE CLEAT SECTIONS WITH THE WALL ENDS TIGHTLY SANDWICHED THEREBETWEEN.