DB-9 male serial to MiniDin-3 female LocalTalk
The First LocalTalk adapter plugs into the DB-9 pin serial printer port (RS-422) on your early Macintosh. It has 2 LocalTalk ports and uses the 3 pin (MiniDin) LocalTalk cable.
Your order may be filled with any of the following Apple numbers: 590-0254-A, 590-0254-B, 590-0563-A
Most of these adapters have permanent marker writing on them.