FIST model 1K clip. Last I checked their website is cludgey as ever but it's there. However I seem to recall I couldn't confirm a 4" N frame was available so I called. I've had about a half dozen of these at different angles for different guns in "extra-thin" Kydex. They can start to crack in about 10 years of frequent use but they're relatively inexpensive. They sew two sheets together instead of folding and makes for pretty thin overall bulk. Clips are like the common today style from (DSG or DCC) with the hook inside the clip.
https://www.fist-holsters.com/