AS568-345 O-Ring

Inside diameter 3.975″
Cross-section 0.210″
Outside diameter 4.395″
Metric (ID × CS) 100.97 × 5.33 mm

OD is derived: ID + 2 × CS = 3.975″ + 2 × 0.210″ = 4.395″.

Neighboring sizes (CS 0.210″ series)

Dash ID OD ID mm vs -345
-343 3.725″ 4.145″ 94.61 ID −0.250″
-344 3.850″ 4.270″ 97.79 ID −0.125″
-345 3.975″ 4.395″ 100.97
-346 4.100″ 4.520″ 104.14 ID +0.125″
-347 4.225″ 4.645″ 107.31 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.