AS568-389 O-Ring

Inside diameter 19.955″
Cross-section 0.210″
Outside diameter 20.375″
Metric (ID × CS) 506.86 × 5.33 mm

OD is derived: ID + 2 × CS = 19.955″ + 2 × 0.210″ = 20.375″.

Neighboring sizes (CS 0.210″ series)

Dash ID OD ID mm vs -389
-387 17.955″ 18.375″ 456.06 ID −2.000″
-388 18.955″ 19.375″ 481.46 ID −1.000″
-389 19.955″ 20.375″ 506.86
-390 20.955″ 21.375″ 532.26 ID +1.000″
-391 21.955″ 22.375″ 557.66 ID +2.000″

Same ID, other cross-sections

Data provenance. SAE AS568, Aerospace Size Standard for O-rings (SAE International). Nominal dimensions per AS568; size tolerances vary by dash number and are not yet cataloged. Groove/gland design depends on the application — consult a gland design reference. See all data sources.