How it connects
Push the plug in (or pull the sleeve back first on manual types) and the locking balls drop into the plug's groove. An internal O-ring seals and a valve shuts off flow when the plug is out. To release, pull the sleeve back.
Male and female halves
This is the female half, called the coupler or socket; it holds the shut-off valve. The male half is the plug or nipple.
Usually connects to
- M-style / Industrial Interchange male plug (nipple) of the same body size
Common sizes
- Most common is 1/4 in body size (1/4 in flow), with 1/8, 1/4, 3/8 and 1/2 in NPT ends. Larger 3/8 and 1/2 in industrial body sizes also exist.
Where it is used
compressed air toolsshop and garage air linespneumatic equipment
Variations
- manual sleeve vs automatic push-type
- safety exhaust couplers
- brass vs steel body
- FNPT, MNPT or hose barb end
How to recognise it
A short brass or steel body with a knurled retaining sleeve and a hex or threaded tail. It is often stamped 'COUPLER M-STYLE' or 'KWIK-CHANGE'. The mouth bore is about 12 mm. A matching M plug is short, with a wide groove near the tip.
Often confused with
| Confused with | How to tell them apart |
|---|---|
| A-style / Aro (ARO 210) coupler | An Aro plug has a longer, narrower nose with a groove in a different place, and it does not lock in an M coupler. |
| T-style / Automotive (Tru-Flate) coupler | A T plug has a long slim nose. The M plug is short and stubby, about 0.45 in across where it meets the plug body. |
| V-style / Hi-Flo (European, ISO 6150 C) coupler | A V-style coupler has a larger bore and a different plug profile, and it is marked V-style or Hi-Flo. |
Also called
Industrial Interchange couplerType D couplerI/M style couplerISO 6150 B-12 couplerMIL-C-4109 coupler1/4 in industrial air coupler
Good to know
M-Style, I-style and Industrial name the same interchangeable profile. Estimated 12 mm mouth and 18 mm insertion are not interface specifications.
Related connections
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