Alpha potentiometers are among the world's most widely used guitar tone and volume controls.
Each pot has an aluminum split shaft that fits a coarse-knurled (18-spline) knob.

Alpha pots are audio taper with standard ±20% resistance tolerance. Each pot includes a flat washer, lock washer, and two hex mounting nuts for custom height adjustment on a pickguard or control plate.
 
500K pots are standard controls for humbuckers. 
 
Shaft Diameter  6mm Split Shaft,coarse knurling
Thread  M8x0.75
Thread Portion Height  3/8" (9.52mm)
Moounting Hole Diameter 5/16" (7.94mm)