... double braiding.3. Middle double bellows.4. Isolate noise,relieve vibration,reduce the stress on the pipesThis series of professional quality ... in installation in an exhaust system to isolate noise, relieve vibration, and reduce the stress on the pipes.a stainless ... bellows for vibration isolation, internal stainless steel braid to reduce noise and/or whistling, and an external stainless steel braid ...