» Compression bellow » Metal free design» Bi-directional» Externally mounted Applications: Corrosive media. This seal has a PTFE Bellow as a compression device. It is designed to seal majority of corrosive chemicals. Composite GFT/PTFE bellow and drive pins help the seal to minimize the face distortions. Being a non pusher seal, dynamic gasketing and hence shaft fretting is eliminated.