SI-601 TB Seal Are Externally Mounted Teflon Bellow Seal. This Seal Designed For Extremely Corrosive Chemica Including Concentrated Acids, Salt, Strong Oxidizing & Reducing Agents & Chemically Active Organic. The Seal Contain PTFE + GFT Composite Bellows Which Is Hydraulically Balanced And Is Machined With High Precision To Form The Prescribed Contour.