CTS 500k/500k dual concentric "stacked" audio taper potentiometer. Allows for volume and tone controls in one 3/8" mounting hole.
Top shaft is 3/16"(4.75mm) diameter and bottom shaft is 17/64"(6.75mm) diameter.
Includes nut and dress washer.

Note : this model is suited to mounting onto a pickguard, not through a guitar body.