This steel brake adapter has a female 3/8-24 inverted flare (convex) port on one end and a 3AN male (3/8-24, 37° convex) on the other end. The 11/16" hex is large enough to support a crush washer (sold separately) when sealing the 3AN male side against a flat faced 3/8-24 port. This adapter also has a groove to accept our Retaining Clip (Part No. 3607-001, sold separately). This allows it to be installed in a 5/8" hole as a bulkhead fitting. Sold individually.
We also offer a similar 3AN Male to 3/8-24 Female Inverted Flare Aluminum Adapter with Frame Weld Tab (Part No. 4651).