As listed
| Field | Value |
|---|---|
| Seller | Aircraft Spruce |
| Standard | AN818 (= MS20818) |
| Form | Coupling nut for flared tube |
| Listing checked | 2026-09-30 |
Taken from Aircraft Spruce's product page on 2026-09-30. Where the listing does not state a figure, this table does not either.
What it is for
The dash number is the tube outside diameter in sixteenths (−4 = 1/4"). A "D" suffix is aluminum, "J" stainless, no suffix steel, as the listing's columns show.
It works with the AN819 sleeve behind the flare. Our roadmap covers AN fitting sizes in a chart page.
Sizes listed
| Steel | Aluminum | Stainless | Tube OD (in.) | Thread |
|---|---|---|---|---|
| 2 | 2D | 2J | 1/8 | 5/16-24 |
| 3 | 3D | 3J | 3/16 | 3/8-24 |
| 4 | 4D | 4J | 1/4 | 7/16-20 |
| 5 | 5D | 5J | 5/16 | 1/2-20 |
| 6 | 6D | 6J | 3/8 | 9/16-18 |
| 8 | 8D | 8J | 1/2 | 3/4-16 |
| 10 | 10D | 10J | 5/8 | 7/8-14 |
| 12 | 12D | 12J | 3/4 | 1-1/16-12 |
| 16 | 16D | 16J | 1 | 1-5/16-12 |
As listed by Aircraft Spruce on 2026-09-30. Check the live listing before ordering: stock and part numbers change.
Where to buy
The link opens Aircraft Spruce's own page for this item, so the price and stock you see are theirs and current. We do not copy prices.
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Sources
- Aircraft Spruce — AN818 Coupling Nut — product listing, checked 2026-09-30.