Vibrant LiteFlex Coupling w/Interlock Liner 2.25in ID x 4.00in LongVibrant Performance LiteFlex Exhaust Couplings feature an internal Stainless Steel Interlock Liner to facilitate smooth exhaust flow. The Interlock Liner also protects the bellows corrugations from elevated exhaust temperatures all while allowing a degree of flexibility required in high performance applications. They feature a lightweight outer wire mesh that limits bellows expansion, as well as providing protection from road debris. LiteFlex Coupling