One-inch drive is the largest square in common industrial use, and the range is deliberately short — there are 2 extension bar lengths, listed below with part numbers.
Why the range is small
A one-inch drive assembly is not selected for convenience, it is selected because a fastener requires torque no smaller drive can carry. That work is specified rather than improvised: an assembly line, a maintenance procedure or a structural bolting spec calls for a particular figure, and the tooling is chosen to deliver it. Nobody needs eight lengths of bar for that; they need the one that reaches the fastener without introducing flex.
Everything here is driven by a machine
Torque at this level comes from a multiplier, a hydraulic wrench or a large pneumatic gun. That changes what an extension bar has to survive: not a person leaning on a handle, but sustained or hammering load applied by something that will not notice resistance. It also means the whole stack must be rated for the driving tool — a component intended for hand use anywhere in the chain becomes the failure point, and at these energies a failure is dangerous rather than inconvenient.
All 2 lengths
| Length | Length (in) | Teng part number | EAN |
|---|---|---|---|
| 200 mm | 7.87 | M110040 | 5020385135024 |
| 400 mm | 15.75 | M110050 | 5020385135031 |
Where this list comes from
Every row is read from the live Teng Tools USA catalogue on the day this page was generated — product record, part number and size taken from the record itself, never transcribed from a printed catalogue or inferred from a pattern. Lengths are as recorded on the product; the inch column is an exact conversion at 25.4 mm to the inch, rounded for display. A size that has been discontinued disappears from this list rather than lingering as a part number you cannot order, which is the failure mode of every static spec sheet.
Handling and storage
These bars are heavy enough that dropping one damages whatever it lands on, including a foot. They also carry their weight a long way from the drive when the assembly is horizontal, so a stack left resting on a fastener will lever itself off. Support the far end while the assembly is being positioned, and store bars where they cannot roll — a rolling one-inch bar on a workshop floor is a genuine trip hazard, not a tidiness complaint.
Large-drive tooling is in sockets and accessories; torque equipment is in torque equipment.