# Air quick-coupler plug profiles: industrial M / H / G, Tru-Flate T, ARO A, European 7.2, Japanese, Lincoln, Schrader (tip diameter and length)

> Which air coupler plug is which: how big are the tips of industrial (Milton M-style), Tru-Flate (T-style), ARO (A-style) and European plugs, and do they interchange?

- Category: Tri-clamp & pipe › Pipe, tube & threads
- Kind: Standard part
- Basis: Park Tool's published tip diameter (A) and tip length (B) table for each plug profile, with naming and standards from Wikipedia, Milton distributor listings, Guardair and Prevost; numbers only
- Page: https://xemstudio.com/objects/air-quick-coupler-plug-profiles/ · JSON: https://xemstudio.com/api/geometry?object=air-quick-coupler-plug-profiles · Plain text: https://xemstudio.com/objects/air-quick-coupler-plug-profiles/sheet.txt
- License: dimension sheet CC BY 4.0 (Xem Studio); files CC BY 4.0 or their publisher's license
- Use in every chat: add https://xemstudio.com/mcp as a connector (https://xemstudio.com/use-with-ai/)

**Exact dimensions.** True size, with no tolerance added.

## Notes

- Plug profiles are distinguished by the tip (the nose that enters the coupler): tip diameter A and tip length B, as Park Tool names them. Two plugs with the same tip diameter are NOT interchangeable if the tip length differs: 1/4 in industrial (M) is 5/16 in × 3/16 in (7.94 × 4.76 mm); 1/4 in ARO (A) is also 5/16 in diameter but 5/16 in (NPT) or 3/8 in (BSPT) long; 1/4 in Tru-Flate (T) is 3/8 in × 1/16 in; 1/4 in European is 3/8 in × 3/16 in. The 'flow size' is the plug and coupler body size (1/4, 3/8 ...), not the thread on the back of the plug.
- Naming. Park Tool uses the Milton letters: M-style (1/4), H-style (3/8), G-style (1/2) for the industrial profile; A-style for ARO; V-style for European. Guardair calls the industrial profile 'Industrial Interchange, also M-style, I/M-style, Type-D' and the European one 'High Flow: V-style, Megaflow, European interchange'. A Milton A-style plug is sold as interchanging with ARO 210 and a Milton T-style plug as interchanging with the Tru-Flate / Parker series (Hi-Line listings). Park Tool and the Hi-Line listing label the Tru-Flate series differently (Park Tool 'automotive'; Hi-Line 'Tru-Flate / Parker industrial interchange series'), so the T-style name is what to match, not the word automotive or industrial.
- Standards (Wikipedia, Air-line fitting): the US industrial 1/4 in (M) profile is listed under A-A-59439, ANSI T3.20.14-1990, MIL-C-4109F and ISO 6150 B, and ISO 6150 B is cited for the US industrial 1/4, 3/8 and 1/2 in profiles; ARO 210 is DN 5.5 and ARO 310 DN 9; the European 7.2 is DN 7.2/7.4 and Eurostandard 10 DN 10; no standard is listed there for the T or A profiles. Prevost's ISO 6150 B safety couplings (ISI 06) have a 6 mm passage and G1/4, G3/8, G1/2 male thread bodies (A 76.3 / 78.3 / 82.3 mm, B 30 mm, C 20 / 23 / 26 mm on the datasheet; the letters are not defined in the text read). The ISO 6150 B plug drawing and the size designations such as B-12 are not in a document we could read, so no ISO plug dimensions are listed.
- Single source for the numbers: Park Tool's table is the only document read that prints tip diameter and length (inch, with the mm it prints); no second maker table was found, so treat the figures as a guide to telling profiles apart, and measure a plug with calipers before ordering the other half. The mm values here are the inch value × 25.4 rounded to 2 decimals; Park Tool's own mm figures are within 0.03 mm of them.
- Not published as numbers in anything read: the groove, shoulder and sleeve geometry, the thread on the back (typically 1/4 or 3/8 NPT, but varies by part) and plug body diameter. No file is drawn. McMaster-Carr sells quick-disconnect plugs and sockets, including ARO style, with per-part STEP; its air-coupling pages are linked, not copied.
- Related: camlock (cam and groove) couplings for liquids and bulk hose: camlock-couplings. Push-to-connect tube fittings for pneumatics: push-to-connect-fitting-sizes.

## Sizes

| profile (Milton letter) | flow size | tip diameter A | tip length B |
|---|---|---|---|
| Industrial | 1/8 in | 1/4 in (6.35 mm) | 1/8 in (3.17 mm) |
| Industrial (Milton M-style) | 1/4 in | 5/16 in (7.94 mm) | 3/16 in (4.76 mm) |
| Industrial (Milton H-style) | 3/8 in | 7/16 in (11.11 mm) | 5/16 in (7.94 mm) |
| Industrial (Milton G-style) | 1/2 in | 9/16 in (14.29 mm) | 3/8 in (9.52 mm) |
| Industrial | 3/4 in | 13/16 in (20.64 mm) | 5/16 in (7.94 mm) |
| Tru-Flate (Milton T-style, automotive) | 1/4 in | 3/8 in (9.52 mm) | 1/16 in (1.59 mm) |
| Tru-Flate (automotive) | 3/8 in | 7/16 in (11.11 mm) | 1/8 in (3.17 mm) |
| Tru-Flate (automotive) | 1/2 in | 9/16 in (14.29 mm) | 1/8 in (3.17 mm) |
| ARO (Milton A-style), NPT | 1/4 in | 5/16 in (7.94 mm) | 5/16 in (7.94 mm) |
| ARO (Milton A-style), BSPT | 1/4 in | 5/16 in (7.94 mm) | 3/8 in (9.52 mm) |
| ARO (Milton A-style), NPT | 3/8 in | 7/16 in (11.11 mm) | 9/16 in (14.29 mm) |
| European (Milton V-style, Megaflow, NT 7.2 / DIN 7.2) | 1/4 in | 3/8 in (9.52 mm) | 3/16 in (4.76 mm) |
| Japanese | 1/4 in | 7/16 in (11.11 mm) | 7/32 in (5.56 mm) |
| Silverline bayonet (UK) | 3/16 in | 5/16 in (7.94 mm) | 11/32 in (8.73 mm) |
| Lincoln | 1/4 in | 9/32 in (7.14 mm) | 3/4 in (19.05 mm) |
| Schrader quick-connect (twist lock) | 1/4 in | 5/16 in (7.94 mm) | 3/4 in (19.05 mm) |
| Schrader quick-connect (twist lock) | 1/2 in | 1/2 in (12.7 mm) | 7/8 in (22.22 mm) |

## Where the files are

- Park Tool: [Adapting the INF-2 for use with different air coupler standards: tip diameter (A) and tip length (B) of industrial, Tru-Flate, ARO, European, Japanese, Lincoln, Silverline and Schrader plugs](https://www.parktool.com/en-int/blog/repair-help/adapting-the-inf-2-for-use-with-different-air-coupler-standards) — web — Maker article; numbers only
- Wikipedia: [Air-line fitting: coupler series (Milton letter, ARO, Parker, Euro), nominal diameters DN, and the standards each is listed under](https://en.wikipedia.org/wiki/Air-line_fitting) — web — Encyclopedia; names and standards only
- Hi-Line: [1/4 MPT Milton A-style, ARO 210 interchange series plugs, plated case-hardened steel (A-style = ARO 210; 300 psi, 34 SCFM)](https://hi-line.com/1-4-mpt-milton-a-style-aro-210-interchange-series-plugs-plated-case-hardened-steel/) — web — Distributor listing; names only
- Hi-Line: [1/4 MPT Milton T-style, Tru-Flate / Parker interchange series plugs, plated case-hardened steel](https://hi-line.com/1-4-fpt-milton-t-style-tru-flate-parker-interchange-series-plugs-plated-case-hardened-steel/) — web — Distributor listing; names only
- Guardair: [Air fittings chart: Industrial Interchange (also M-style, I/M-style, Type-D) and High Flow (V-style, Megaflow, European interchange) plugs, 1/4 and 3/8 in](https://guardair.com/pages/air-fittings-chart) — web — Maker chart; names only
- Prevost: [Safety quick couplings ISI 06, ISO 6150 B profile: G1/4, G3/8, G1/2 male thread couplers, 6 mm passage](https://medias-prevost.nextpage.fr/Fiches%20produits%5CINT%5C69098_Parallel_male_thread_coupler_int.pdf) — web — Maker datasheet; numbers only
- McMaster-Carr: [Air hose couplings (quick-disconnect plugs and sockets) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/air-hose-couplings) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- McMaster-Carr: [ARO-style quick-disconnect hose fittings (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/products/hose-fittings/quick-disconnect-style~aro) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)
- McMaster-Carr: [Quick-disconnect hose sockets (couplers) (free STEP/IGES per part, for your own design use; no redistribution)](https://www.mcmaster.com/quick-disconnect-hose-sockets) — STEP, IGES, PDF — McMaster-Carr site terms: personal design use, no redistribution (verify at link)

## Questions

**What is the difference between M-style and T-style air couplers?**

Same 1/4 in flow size but different tips: M (industrial) is 5/16 in diameter and 3/16 in long; T (Tru-Flate) is 3/8 in diameter and 1/16 in long (Park Tool). They do not interchange.

**Do M-style and A-style plugs interchange?**

No. Both have a 5/16 in tip diameter, but the A (ARO) tip is longer: 5/16 in (NPT) or 3/8 in (BSPT) against 3/16 in for the industrial M tip.

**What is a 3/8 in H-style plug?**

Milton's name for the 3/8 in industrial (Industrial Interchange) profile: 7/16 in tip diameter, 5/16 in tip length (Park Tool).

**Which profile is ISO 6150 B?**

Wikipedia lists ISO 6150 B against the US industrial 1/4, 3/8 and 1/2 in profiles (the M, H and G profiles); the standard's own drawing was not readable.

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