Gasket is 2" wide x 1/16" thick. Order the correct length for your needs. Add the lengths of your catalyst's four sides to determine length needed You may secure gasket around combustor using masking tape Expanding gasket provides a tight seal around catalyst Midwest Hearth replacement interam gasket for wood stove catalytic combustors. This gasket measures 2 inches wide and is 1/16 inch thick. Please measure the sum total of all four sides of your combustor to ensure you order the correct length. Always round up, this gasket may be trimmed with a scissors or blade to the exact length you need. Secure the gasket to the perimeter of your catalyst using making tape. The making tape will burn away after first use, and will not affect the performance of your stove or combustor.