MBRP RESONATOR, STAINLESS STEEL, NATURAL FINISH, SOLD INDIVIDUALLY -- 2.5 in. inlet; 2.5 in. outlet; Single inlet and outlet configuration; 4 in. shell diameter, 16 in. body length, 20 in. overall length; Made of tough and durable polished T-304 stainless steel; Designed to modify sound levels to where you want them.