AS568-027 O-Ring — 1.301 × 0.070 in
The -027 is a 000 series size: a 0.070 in cord on a 1.301 in inside diameter, which is 1.78 mm on 33.05 mm. Its outside diameter is 1.441 in (36.6 mm), derived as ID + 2 × cord.
Dimensionsthe two cells the standard fixes, and one derived value
| Dimension | Inches (AS568) | Millimetres (converted) |
|---|---|---|
| Inside diameter d₁ (ID) | 1.301 | 33.05 |
| Cross-section d₂ (cord) | 0.070 | 1.78 |
| Outside diameter (reference) | 1.441 | 36.6 |
| Inside diameter tolerance | ±0.011 | ±0.28 |
| Cross-section tolerance | ±0.003 | ±0.08 |
Inches are the standard’s own units; millimetre values are conversions — inch × 25.4, rounded to two decimals — and not the ISO 3601-1 metric sizes. Outside diameter is a reference value derived as ID + 2 × cross-section; the two diameters the standard fixes are the inside diameter and the cord.
Reading the designationnothing in AS568-027 is a dimension
The -027 is a lookup key. Its first digit — 0 — puts it in the 000 Series family, and the remaining two digits are its position inside that family counted upwards by inside diameter, which makes it number 27 of the 50 sizes here. Neither digit group carries a size: the -027 is 1.301 in on a 0.070 in cord, and a dash number one away from it can differ by a hundredth of an inch or by a quarter of one.