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AS568-128 O-Ring Size
100 series · 3/32" cross section · Hydraulics, pumps, valves
Inside diameter × cross section
37.77 × 2.62 mm
1.487″ × 0.103″ ·
outside diameter 43.0 mm (1.693″)
Dimensions
| Dimension | Inches | Millimetres |
|---|---|---|
| Inside diameter (ID) | 1.487″ | 37.77 mm |
| Cross section (CS) | 0.103″ | 2.62 mm |
| Outside diameter (OD) | 1.693″ | 43.0 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 37.77 mm, because compression set is permanent. If your measurement came in a little under this and the cross section roughly matches, -128 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) |
|---|---|---|---|
| -129 | 39.34 | 1.549″ | 44.58 |
| -127 | 36.17 | 1.424″ | 41.4 |
| -126 | 34.59 | 1.362″ | 39.83 |
| -130 | 40.94 | 1.612″ | 46.18 |