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AS568-208 O-Ring Size
200 series · 1/8" cross section · General purpose, cylinders
Inside diameter × cross section
15.47 × 3.53 mm
0.609″ × 0.139″ ·
outside diameter 22.53 mm (0.887″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 0.609″ | 15.47 mm |
| Cross section (CS) | 0.139″ | 3.53 mm |
| Outside diameter (OD) | 0.887″ | 22.53 mm |
Outside diameter is not measured, it is derived: OD = ID + 2 × CS.
If your measured OD disagrees with this, trust the ID and cross section — measuring
across the outside of a flexible ring is the least reliable of the three.
If you measured a used one
A ring pulled out of service will measure smaller than 15.47 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -208 is very likely still the correct part. Ordering the size your worn ring measures is how the same failure repeats. More on this →
Nearby sizes in the 200 series
These share the same 1/8" cross section, so if the thickness is right but the diameter is off, your ring is probably one of these.
| Dash | ID (mm) | ID (in) | OD (mm) |
|---|---|---|---|
| -209 | 17.04 | 0.671″ | 24.1 |
| -207 | 13.87 | 0.546″ | 20.93 |
| -206 | 12.29 | 0.484″ | 19.35 |
| -210 | 18.64 | 0.734″ | 25.7 |