AS568-277 O-Ring

Inside diameter 11.484″
Cross-section 0.139″
Outside diameter 11.762″
Metric (ID × CS) 291.69 × 3.53 mm

OD is derived: ID + 2 × CS = 11.484″ + 2 × 0.139″ = 11.762″.

Neighboring sizes (CS 0.139″ series)

Dash ID OD ID mm vs -277
-275 10.484″ 10.762″ 266.29 ID −1.000″
-276 10.984″ 11.262″ 278.99 ID −0.500″
-277 11.484″ 11.762″ 291.69
-278 11.984″ 12.262″ 304.39 ID +0.500″
-279 12.984″ 13.262″ 329.79 ID +1.500″
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.