ALUMINUM. MOST HAVE AN OPTIONAL STAINLESS SHEET COVERING ONE SURFACE. A FEW HAVE SIX DRILLED AND TAPPED MOUNTING HOLES; MOST HAVE SOME DRILLED AND TAPPED HOLES ON THE 26.25” SIDES. 0.75” PORTS ON SAME 20.25” SIDE APPROX 3” FROM EACH EDGE. THERMOCOUPLE PORT ON SAME SIDE AS PORTS APPROX 5.5” FROM THE EDGE. QTY 27. ITEM #2446.