Two control knobs, military style. To complement my Large Military-style tuning knob.
Skirt diameter 28.5 mm. The low profile one is about 16 mm high and the taller one is about 22 mm high.
Fits 1/4" shaft size. Some margin is allowed for non-recessed shaft components.

Insert: 1/4" plated brass Dura-Collar, Dubro. Run in grubscrew more than flush and orient toward hole, then press in with vice or c-clamp.
Placing a donut of felt or plastic sheet between the knob skirt and radio face may assure smooth spinning.