Product Details: Prepare your semi truck to be ready for the long haul with seamless exhaust connections, with the OTR 5" to 4" Aluminized Exhaust Reducer with Expertise Built In™. By utilizing a sophisticated design, this replacement piece helps reduce the diameter of an exhaust pipe so that it can tightly seal with smaller-sized components. Manufactured with an aluminized pipe with enhanced corrosion resistance. FleetPride is your First Click in Heavy Duty®.