Here is the description from Amazon...the key is the 1/4-20” thread insert...at least on my Beckson ports.Really like your idea, Greg. Must get me some knobs.
DimcoGray
DimcoGray Black Phenolic 4 Prong Knob Female, Thru Hole Brass Insert: 1/4-20" Thread x 1/2" Depth, 1-1/4" Diameter x 7/8" Height x 5/8" Hub Dia x 3/8 Hub Length (Pack of 10)DimcoGray Black Phenolic 4 Prong Knob Female, Thru Hole Brass Insert: 1/4-20" Thread x 1/2" Depth, 1-1/4" Diameter x 7/8" Height x 5/8" Hub Dia x 3/8 Hub Length (Pack of 10)
Greg