Dual Concentric knobs. The larger of the two has a 1/4" shaft diameter, white indicator line, black glossy finish, with 2 set screws. The smaller of the two has a 1/8" shaft diameter, spun aluminum insert, black indicator line, black glossy finish, with 2 set screws.

If you're looking for these, you know they're hard to come by.  I needed a couple hundred of these for project, and ended up getting these manufactured.  I have several hundred available...