AS568-139 O-Ring

Inside diameter 2.175″
Cross-section 0.103″
Outside diameter 2.381″
Metric (ID × CS) 55.24 × 2.62 mm

OD is derived: ID + 2 × CS = 2.175″ + 2 × 0.103″ = 2.381″.

Neighboring sizes (CS 0.103″ series)

Dash ID OD ID mm vs -139
-137 2.050″ 2.256″ 52.07 ID −0.125″
-138 2.112″ 2.318″ 53.64 ID −0.063″
-139 2.175″ 2.381″ 55.24
-140 2.237″ 2.443″ 56.82 ID +0.062″
-141 2.300″ 2.506″ 58.42 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.