AS568-387 O-Ring

Inside diameter 17.955″
Cross-section 0.210″
Outside diameter 18.375″
Metric (ID × CS) 456.06 × 5.33 mm

OD is derived: ID + 2 × CS = 17.955″ + 2 × 0.210″ = 18.375″.

Neighboring sizes (CS 0.210″ series)

Dash ID OD ID mm vs -387
-385 15.955″ 16.375″ 405.26 ID −2.000″
-386 16.955″ 17.375″ 430.66 ID −1.000″
-387 17.955″ 18.375″ 456.06
-388 18.955″ 19.375″ 481.46 ID +1.000″
-389 19.955″ 20.375″ 506.86 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.