It's an orange drop (well it's orange). ABout 2cm's long and the values on it are:
715P200V 104J 0239
Can I use this on my strat tone control? I've heard that it can make a difference so I thought I'd try it out. I can't tell from the pics on the internet whether this .1uf or not which I think is the one I need.

Apologies for my ignorance I have tried searching

I have another on that is yellow .001/20 1000v?
Thanks

104J means that its 10 followed by 4 zero's. That's .1uf/.1mf and J is a tolerance rating (as an example, +/-10% or +/-20%, but I'm not sure what tolerance "J" is)

715P is the Vishay/Sprague model number (so yes, it's an Orange Drop). 200V means it can handle up to 200 volts. The last 4 numbers are a batch code/production number.

.1uf is the value Fender used back in the '50s/early '60s (and reissues). It starts passing signal at lower frequencies than a .047, which in turn passes lower frequencies than a .022, so a .1 is the darkest sound of the three as you turn down the knob.

Some people like that, but for most of us it's way too dark sounding to be usable. That's why Fender switched to .047 as their "standard" cap value. If your Strat already has a .1 cap, you can swap in the Orange Drop to see if you hear a difference in cap types. But if your Strat has a more common .047, the main difference you'll hear will be due to the different cap value rather than the different cap type.

.001/20 is most likely a .001uf cap with a 20% tolerance. That'll only affect the highest frequencies. Most often that value is used for a treble bleed on the volume control, but some people do use them for tone controls. As a tone control it'd be pretty subtle and just roll off some of the "fizz" when you use a lot of distortion.

The voltage rating doesn't matter much (if at all) for a guitar tone circuit. Higher isn't better or worse.

Brilliant! Thanks so much!