17 x 18 - Heavy Duty 4 Pass with Brackets17 x 18 Heavy Duty 4 Pass with Brackets TYPE: Parallel Flow CORE LENGTH: 18'' CORE HEIGHT: 17'' CORE THICKNESS: 1'' OVERALL LENGTH: 22 1 2'' OVERALL HEIGHT: 18 1 8'' OVERALL THICKNESS: 1 1 4'' FITTING INLET: #8 Male Insert O Ring FITTING OUTLET: #6 Male Insert O Ring FINS PER INCH: 10 Fins per Inch NUMBER OF ROWS: 4 Pass Parallel Flow, Non Serviceable Design Non Louvered Fins for Higher Efficiency and Harsh Environment Heavy Duty with 1'' Thick Multi