Deep sockets in the small imperial sizes reach nuts on threaded rod, terminal studs and clamp bolts where a regular socket bottoms out. This is the complete list of 9 in 1/4 inch drive six point, with part numbers.
Where small deep SAE sockets earn their keep
Imperial threaded rod is still the standard way to hang and brace things in a building, and the nuts on it are almost always run some distance down the thread. The same applies to older electrical panels, marine terminal blocks and any assembly adjusted by running a nut along a stud. In all of them the nut is small, the exposed thread is long, and a regular socket cannot reach past it — the deep socket is not a convenience, it is the only tool that fits.
Threaded rod chews sockets
Running a deep socket repeatedly over exposed thread wears the inside of the bore, and on the smallest sizes there is not much material to lose. Two habits extend the life considerably: keep the socket square as it goes on rather than screwing it down at an angle, and clear the bore of thread debris and zinc afterwards. A socket that has picked up a burr inside will not seat fully on the next nut, and a socket that is not fully seated is loading the top corners of the hex.
All 9 deep SAE sizes
| Size | Decimal inch | Millimetres | Teng part number | EAN |
|---|---|---|---|---|
| 3/16 in | 0.1875 | 4.76 | M140206-C | 5020385132313 |
| 7/32 in | 0.2188 | 5.56 | M140207-C | 5020385132900 |
| 1/4 in | 0.2500 | 6.35 | M140208-C | 5020385132320 |
| 9/32 in | 0.2813 | 7.14 | M140209-C | 5020385132917 |
| 5/16 in | 0.3125 | 7.94 | M140210-C | 5020385132337 |
| 11/32 in | 0.3438 | 8.73 | M140211-C | 5020385135659 |
| 3/8 in | 0.3750 | 9.52 | M140212-C | 5020385132344 |
| 7/16 in | 0.4375 | 11.11 | M140214-C | 5020385132351 |
| 1/2 in | 0.5000 | 12.70 | M140216-C | 5020385132368 |
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. Deep and regular sockets in the same nominal size carry different part numbers and are listed separately. 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. AF means "across flats": the distance between two opposite faces of the hex, which is what the socket actually grips. Millimetre equivalents are exact conversions at 25.4 mm to the inch and are provided for cross-referencing only.
Length versus access
A deep socket takes room above the fastener as well as around it, and on a small drive the assembly is long relative to the space it usually works in. Where there is not enough headroom the answer is rarely a longer tool: a stubby ratchet, a short extension taken off the side, or a wrench on the nut and a screwdriver holding the stud will all get a captive nut moving where a deep socket and a full-length ratchet physically cannot be brought to bear.
Sockets and bars are in sockets and accessories; ratchets are in ratchets.