Knurled knob
Black phenolic plastic.
Brass insert with tapped blind hole.
Brass insert, smooth blind hole and tapped grub screw.
Brass insert with tapped through hole.
Threaded zinc plated steel stud.
Three-lobe knob
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.