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AS568-158 O-Ring Size
100 series · 3/32" cross section · Hydraulics, pumps, valves
Inside diameter × cross section
120.32 × 2.62 mm
4.737″ × 0.103″ ·
outside diameter 125.55 mm (4.943″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 4.737″ | 120.32 mm |
| Cross section (CS) | 0.103″ | 2.62 mm |
| Outside diameter (OD) | 4.943″ | 125.55 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 120.32 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -158 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 100 series
These share the same 3/32" 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) |
|---|---|---|---|
| -157 | 113.97 | 4.487″ | 119.2 |
| -159 | 126.67 | 4.987″ | 131.9 |
| -156 | 107.62 | 4.237″ | 112.85 |
| -160 | 133.02 | 5.237″ | 138.25 |