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AS568-242 O-Ring Size
200 series · 1/8" cross section · General purpose, cylinders
Inside diameter × cross section
101.19 × 3.53 mm
3.984″ × 0.139″ ·
outside diameter 108.25 mm (4.262″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 3.984″ | 101.19 mm |
| Cross section (CS) | 0.139″ | 3.53 mm |
| Outside diameter (OD) | 4.262″ | 108.25 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 101.19 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -242 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) |
|---|---|---|---|
| -241 | 98.02 | 3.859″ | 105.08 |
| -243 | 104.37 | 4.109″ | 111.43 |
| -240 | 94.84 | 3.734″ | 101.9 |
| -244 | 107.54 | 4.234″ | 114.6 |