DuraVent 2" 4" Inner Diameter PolyPro Horizontal Termination Kit without Adapters Size:3" Actual Framing Front Width (A) btu43800 Actual Framing Front Width (A) 44 1 2" (1130mm) 45 1 2" (1158mm) Height (B) 59 1 4" (1505mm) 59 3 4" (1518mm] Depth (C) 27 1 2" (699mm) 28" (711mm) Rear Width (D) 28 5 8" (727mm) 45 1 2" (1158mm) Fireplace Opening (E x F) 36" x 28 1 2" The Vent Adapter Accessory is used to compensate for the extra space left around the vent hole when replacing a furnace with a larger vent opening With a broad range of engineered venting products Polypropylene has a higher operating temperature limit of 230°F 110°C (PVC is 149°F 65°C max and CPVC is 194°F 90°C)