These are both connected to the cable screen. This has the effect of enclosing all of the guitar’s electronics in a conductive box which is connected to ground. Any noise that would previously have been picked up and amplified along with the guitar signal is now mostly shunted to ground, giving a much cleaner signal.
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Shielding attenuation: Attenuation of 39 dB (shielding effectiveness of 99.98 %) in one layer. Guitar Graphite Shielding Paint Kit. attenuation of 46 dB (shielding effectiveness of 99.995 %) with two layers.
eBay
These are both connected to the cable screen. This has the effect of enclosing all of the guitar’s electronics in a conductive box which is connected to ground. Any noise that would previously have been picked up and amplified along with the guitar signal is now mostly shunted to ground, giving a much cleaner signal.
eBay