500K audio potentiometer, standard length bushing.375", 3/8" diameter. CTS is (and has been since the 50's) a factory standard for most USA brands like Fender and Gibson. Value: Typically 250K pots are used for single coil pickups and 500K pots for humbucker pickups. The bigger the resistence value, the brighter the sound will be/ less highs will bleed off. 1MEG can be used to make humbuckers sound brighter. Taper: The taper of a pot refers to the way its resistance changes as the shaft is rotated. A linear taper pot will work in a linear way related to shaft rotation. As the human ear is not linear in response to increasing volume an audio or logarithmic pot will work best for volume applications. Shaft: A split, knurled shaft will hold most knobs. Sometimes the knob is mounted using a set screw. You should order a solid shaft pot, or align the set screw with the split for correct mounting. Bushing: The standard bushing diameter is 3/8" or 9,5mm, used in most made in USA guitars.