Knurled knob
Black phenolic plastic.
Brass insert, smooth blind hole and tapped grub screw.
Brass insert with tapped through hole.
Threaded zinc plated steel stud.
Three-lobe knob
Brass insert with tapped blind hole.
Zinc plated steel outcropping insert.
Four-lobe knob
Zinc plated steel insert with tapped blind hole.
Six-lobe knob
Outcropping brass insert with tapped blind hole.
Five-lobe knob
Zinc plated steel hub.