Seat Back Height Adjusting screws in stainless otherwise as original with a 5/16" dia  thread, a  knurled edge & slight dome on top, highly polished - these are suitable for the DB2 & DB2/4MkI models.

We make the other type with a 3/8" dia thread for DB2/4 MkII & DB MkIII  models.

Original one on right in photo