A very high quality- full size ALPHA brand 250k volume pot- Real high Quality Potentiometers
, smooth as silk, reliable as heck, solders like a champ. I've used about a bazillion of these over the past few years and find them to be far preferable to the "mystery" 250k pots sold by a certain well known importer.
These are split shaft but will work both with push on knobs and knobs with a setscrew
Shaft size: 7.80mm