Vintage black Bakelite knobs  3/8" shaft screw down type with screw. 

Approx measurements..

The knob is 1.305" or 33.15mm long 0.63" high and the hole is stepped

The widest is 0.375"; (3/8") or 9.53mm

Middle is 0.2"; or 5.08mm

Narrowest is 0.15"; or 3.84mm

I'm told the screw is a 6ANF (American National Fine) with 40 TPI and it is 0.45" or 11.44mm long

Used, military surplus, will sell tidiest ones first and might even give them a clean to remove decades of dust

I have more vintage Bulgin and Bakelite items listed