Mighty Therm, Complete Heat Exchanger Assembly (single pass, 18 tube), 4500I/4000E. LAARS Code Compliant ASME Heat Exchangers with Headers Built in accordance w/the requirements of the ASME Boiler and Pressure Vessel Code. Individually serialized w/H-4 data reports on file as required by section HG-520.2 and HG-531.