The shaft is long enough for rear-mounted controls and come with two nuts and a washer so they can also be used on pickguards.
Usually, 250k pots are used for single coil pickups and 500k pots are used with humbucker pickups. The graph below shows the difference between Linear and Volumetric. Volumetric has a softer incline when the pot is turned while the Linear incline is straight. Linear is usually more desirable for tone pots.



