AS568-138 O-Ring

Inside diameter 2.112″
Cross-section 0.103″
Outside diameter 2.318″
Metric (ID × CS) 53.64 × 2.62 mm

OD is derived: ID + 2 × CS = 2.112″ + 2 × 0.103″ = 2.318″.

Neighboring sizes (CS 0.103″ series)

Dash ID OD ID mm vs -138
-136 1.987″ 2.193″ 50.47 ID −0.125″
-137 2.050″ 2.256″ 52.07 ID −0.062″
-138 2.112″ 2.318″ 53.64
-139 2.175″ 2.381″ 55.24 ID +0.063″
-140 2.237″ 2.443″ 56.82 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.