Squirrelly 3" x 4" Inch Stainless Steel Cat-Backs Headers Exhaust Flex Pipe Stainless Steel Interlocking Liner Coupler High Performance Turbo Downpipes Applications Flex couplers are used to isolate engine vibration to your exhaust components, and prevent cracks in your downpipes, cat-backs headers and turbo manifolds. We have introduced Stainless Steel Flex Couplers that have bellows with interlocking lining to help increased exhaust flow through the coupler, and prevent excessive back pressure to build. These are the only type of flex coupler that can withstand high pre-turbo exhaust temperatures, meaning you can use these flex couplers when complex turbo header designs are needed to prevent turbo header cracks. Perfect for turbo downpipes! Features: We have introduced Stainless Steel Flex Couplers that have bellows with interlocking lining to help increased exhaust flow through the coupler, and prevent excessive back pressure to build. Made of 304 stainless steel throughout, 409 steel weld rings. Made to handle forced induction turbo and supercharged vehicles. Interlocking lining. Nonmagnetic. 3" x 4" long.