Find Your Air Coupler Interchange
Air couplers and plugs only fit when they share the same interchange profile, and three of the common ones look nearly identical. Answer three questions and this tells you what you have, what fits it, and what to buy so everything in the garage snaps together.
Industrial Supply World is reader-supported. Some links below are affiliate links or go to hpcouplers.com, our own store. That never changes the answer the tool gives you.
What are you trying to match?
Where did it come from, or what is stamped on it?
Milton stamps a letter on most plugs. Other brands follow the same families.
What body size?
Body size is the air passage, not the thread. Almost every home garage is 1/4". If the plug nose is noticeably fatter than a pencil, it is 3/8" or 1/2".
Identify it by the plug nose
Look at the male plug (if you only have a coupler, borrow any plug that fits it). Compare the nose to these:
The five air interchanges at a glance
| Interchange | Also called | Where you meet it | Foster series |
|---|---|---|---|
| Industrial (I/M) | Milton M, Type D, M-style | Hardware-store kits, most compressors | 3 Series (1/4"), 4 Series (3/8"), 5 Series (1/2") |
| Automotive | Tru-Flate, Milton T, Type C | Tire and auto shops | TF Series |
| ARO 210 | Milton A, Type A | Older industrial equipment | 210 Series (1/4"), 310 Series (3/8") |
| Lincoln | Milton L, Type B, long nose | Lube equipment, some plants | LN Series |
| V-style | Milton V, Type V, high flow | Impact wrenches that starve on I/M | Ask us; we stock high-flow options |
A universal coupler accepts Industrial, Automotive and ARO plugs. Nothing else crosses over.
Send us a photo
Lay the plug on a ruler, take one photo, and email it to support@industrialsupplyworld.com. We identify a few of these every week and will tell you exactly what it is and what fits.
Industrial Supply World is run by Mid-States Industrial Sales, a 40-year industrial distributor in Elgin, Illinois, which also operates hpcouplers.com.