Orange Drop tone capacitors - Various values
These are the classic Sprague Orange Drop capacitors in .0012uF, .001uF, .015uF, .022uF, .033uF, .047uF and .1uF values. Audio grade Polypropylene dielectric material provides a smooth, wah type tone with no sonic impurities.
They're available in either .0012uF, .001uF, .015uF, .022uF, .033uF, .047uF and .1uF values.
.001uF & .0012uF are commonly used for treble bleed circuits.
As a rule the general recommendation is .015uF or .022uF for humbuckers, .047uF for single coils, .033uF in traditional Jazzmaster lead circuits and .1uF is a traditional value found in 50s and 60s Fender Tele and Stratocasters for example.
Which is 'correct' so to speak is usually based off the pickup manufacturers recommendations, but you can of course use whichever you choose for the given application. I personally prefer .022uF for both single coil and humbuckers for example, the reason being that a .022uF will 'roll off' less treble than a .047uF, making the pot 'sweep' sound a touch more gradual. A .047uF will be an ever so slightly 'steeper' roll off of trebles but has become the 'standard' often found in Strats and Teles with Single coils. The .015uF is also an interesting choice for Les Paul players looking to achieve that Eric Clapton 'woman' tone you hear so much about. It's personal preference, but first port of call would be to check out your pickup manufacturers recommendation and go from there. For reference, all McNelly Pickups are recommended to pair with .022uF capacitors. Hope this helps!