As fitted to the the SB1, SB2, initial versions of the Stroller, Shadow, Duotone, and potentially other models. In use as late as early 1963. Diameter (at widest point) 24.6mm, height 12.5mm. Grub screw, slotted head, 2.7mm x 6.1mm.
List of Vox control knobs
$100
$69
$139
$50
$125
$69