Four-lobe knob
Black phenolic plastic.
Zinc plated steel insert with tapped blind hole.
Threaded zinc plated steel stud.
Embossed knob
Black thermoplastic.
Brass insert with tapped blind hole.
Knurled knob
Brass insert with tapped through hole.
Six-lobe knob
Outcropping brass insert with tapped blind hole.
Black thermoplastic, mat.
Black thermoplastic, glass fiber reinforced, mat.