Reversible design for installation flexibility. The 401338 resonator is ideal for taking a loud system down a notch. It can be used alone in a single exhaust system or in pairs in a dual system. 100% welded construction for strength. It features a straight through performance design and is constructed of T-304 stainless steel for high durability. It utilizes continuous -filament fiber (CFF) acoustic material for sound control. As with all Borla? mufflers and resonators, it is made the USA and is covered by the Million Mile Warranty.