Combustion chamber 337350, chamber support board, refractory cement, instructions. Combustion chamber is 19 3/8'' x 19-3/8'' x 18'' and 1'' thick. FIT: Fits all Thermo-Dynamics S series boilers including S-85, S-100, S-110, S-125, S-135, S-150, STR-85, STR-100, STR-110, STR-125, STR-135 and STR-150