2103-389 PTFE S/T BUP FDA

This PTFE 55D Backup Ring, item TST389, is designed for buyers who need a clear specification match for anti-extrusion support behind O-rings in high-pressure hydraulic and pneumatic glands. The item is specified by AS568-389; 19.953 inch (506.81 mm) ID x 0.21 inch (5.33 mm) CS; 20.373 inch (517.47 mm) OD, with 20 inch nominal ID; 3/16 inch nominal CS for cross-reference against common gland and replacement dimensions. Its PTFE material provides chemical resistance, low friction and low surface energy in demanding static sealing applications. It is with a listed temperature range of -65°F (-53.9°C) to 500°F (260°C), which can help narrow material selection for heat, cold or process exposure. The white color and round profile provide a practical visual identifier during receiving, stocking and installation. As a backup ring, it works with a primary O-ring to help limit extrusion into clearance gaps under pressure. The each-unit format supports precise replacement, kitting, resale and job-specific purchasing. Common purchasing identifiers for this product include the material name, O-ring type, dimensional size, hardness and intended sealing application. Those attributes make the item easier to compare for maintenance, OEM production, MRO replacement and reseller catalog use.