Core size: 460mm * 537mm ( 18.1″ * 21.1″ ), Overall size: 613mm * 651mm ( 24.1″ * 25.6″ ), Inlet/Outlet: 38mm / 38mm ( 1.5″ 1.5″ ); PLEASE Check the Pictures carefully before you buy to avoid any mistake, especially the location of inlet/outlet, it might be different from yours;