AS568-242 O-Ring

Inside diameter 3.984″
Cross-section 0.139″
Outside diameter 4.262″
Metric (ID × CS) 101.19 × 3.53 mm

OD is derived: ID + 2 × CS = 3.984″ + 2 × 0.139″ = 4.262″.

Neighboring sizes (CS 0.139″ series)

Dash ID OD ID mm vs -242
-240 3.734″ 4.012″ 94.84 ID −0.250″
-241 3.859″ 4.137″ 98.02 ID −0.125″
-242 3.984″ 4.262″ 101.19
-243 4.109″ 4.387″ 104.37 ID +0.125″
-244 4.234″ 4.512″ 107.54 ID +0.250″
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.