AS568-438 O-Ring

Inside diameter 6.225″
Cross-section 0.275″
Outside diameter 6.775″
Metric (ID × CS) 158.11 × 6.99 mm

OD is derived: ID + 2 × CS = 6.225″ + 2 × 0.275″ = 6.775″.

Neighboring sizes (CS 0.275″ series)

Dash ID OD ID mm vs -438
-436 5.850″ 6.400″ 148.59 ID −0.375″
-437 5.975″ 6.525″ 151.76 ID −0.250″
-438 6.225″ 6.775″ 158.11
-439 6.475″ 7.025″ 164.46 ID +0.250″
-440 6.725″ 7.275″ 170.81 ID +0.500″

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.