AS568-351 O-Ring

Inside diameter 4.725″
Cross-section 0.210″
Outside diameter 5.145″
Metric (ID × CS) 120.01 × 5.33 mm

OD is derived: ID + 2 × CS = 4.725″ + 2 × 0.210″ = 5.145″.

Neighboring sizes (CS 0.210″ series)

Dash ID OD ID mm vs -351
-349 4.475″ 4.895″ 113.66 ID −0.250″
-350 4.600″ 5.020″ 116.84 ID −0.125″
-351 4.725″ 5.145″ 120.01
-352 4.850″ 5.270″ 123.19 ID +0.125″
-353 4.975″ 5.395″ 126.36 ID +0.250″

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.