Developed for truck applications and other applications that require a long body muffler. Un-Notched necks are designed for weld in installation. If clamping, use 3" wide band clamps. Alternate muffler with Notched necks is 401625. Use 1" wide band clamps. Reversible design for installation flexibility. High-quality T-304 austenitic stainless steel will never rust. 100% welded construction for strength. Free Flow design for improved performance. High-temperature continuous-filament fiber (CFF) acoustic material for sound control. Natural mill finish can be brushed or polished prior to installation. Best of all, it's made in the USA and backed by Borla(r)'s Million-Mile warranty. Just what you'd expect from the world's most experienced (and most winning) exhaust brand.