Replacement (Canned) Catalytic Combustor with a Metal Band for Vermont Castings Wood Stoves and Fireplaces. It measures 2-1/2" wide x 12-3/4" long x 1" thick. The ceramic catalytic combustor has 16 cells per square inch, and the metal combustor has 50 cells per square inch. Replacing your old combustor will help you improve your stove's efficiency, saving you money and producing less pollution.