Three-eighths drive covers most of the work in a vehicle, and its extension bars are the ones that get used daily. This is the complete list of 5 lengths in the range, with the Teng part number for each.
Length changes what the tool feels like
A short bar exists to lift the ratchet head clear of an obstruction beside the fastener, and it barely changes the feel. A long bar exists to reach past something in front of the fastener, and it changes the feel considerably: the bar winds up before the fastener turns, so the ratchet is already loaded when the nut breaks free and the handle moves further and faster than expected. Knowing which of those two jobs you are doing tells you which bar to pick up.
The bar is not the weak point, the joint is
Bars themselves rarely fail. What fails is the square at either end, and it fails when the assembly is loaded off axis — which is exactly what happens when a long bar is pulled sideways to clear an obstruction. Keeping the bar in line with the fastener while applying torque is the single habit that makes extension bars last, and it is also what keeps the socket square on the hex, so it protects the fastener at the same time.
All 5 lengths
| Length | Length (in) | Teng part number | EAN |
|---|---|---|---|
| 75 mm | 2.95 | M380020-C | 5020385130227 |
| 125 mm | 4.92 | M380023-C | 5020385130241 |
| 150 mm | 5.91 | M380021-C | 5020385130234 |
| 254 mm | 10.00 | M380022-C | 5020385132924 |
| 500 mm | 19.69 | M380024-C | 5020385132375 |
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 record; the inch column is an exact conversion, 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.
Extension bars and torque wrenches
An extension bar in line with the drive does not change the torque a wrench applies, because it adds no lever arm — the common belief that it does is wrong. What genuinely does change the reading is an offset adaptor such as a crow foot, which moves the fastener away from the wrench axis and needs the setting recalculated. A plain in-line bar can be used with a torque wrench without adjustment, though the extra wind-up makes the click harder to feel.
Bars are in sockets and accessories; torque wrenches are in torque equipment.