Solder lug terminal.
1/4" (6.35mm) round shaft.
These could be a mix of Alpha, Mammoth, or Cusack brand, all have the same dimensions. Equivalent to standard Alpha RV16AF-10-15R1.
Don't forget dust seals!
Specs of Cusack pots (Image changes to Cusack pot if available for selected value):
Tolerance: <10% typical, 20% max
Insulation wafer: Fiberglass (extremly strong compared to orange phenolic resin wafer)
Insulation resistance 100MΩ min at 500vDC
Power: .1w B taper, .05w A/C/W
Rotation life: 10,000 cycles minimum
Rotation angle: 300° (+/- 5°)
Rotation torque: 50 gf·cm (+/- 20 gf·cm)