AS568-318 O-Ring

Inside diameter 0.975″
Cross-section 0.210″
Outside diameter 1.395″
Metric (ID × CS) 24.76 × 5.33 mm

OD is derived: ID + 2 × CS = 0.975″ + 2 × 0.210″ = 1.395″.

Neighboring sizes (CS 0.210″ series)

Dash ID OD ID mm vs -318
-316 0.850″ 1.270″ 21.59 ID −0.125″
-317 0.912″ 1.332″ 23.16 ID −0.063″
-318 0.975″ 1.395″ 24.76
-319 1.037″ 1.457″ 26.34 ID +0.062″
-320 1.100″ 1.520″ 27.94 ID +0.125″
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.