Hey @flowcharts - Yep, it is flexo anti-stat, formerly known as flexo conductive. The conductivity is interesting- there is too much resistance at DC to get a connection when you probe either side. So it’s not conductive the way any tinned copper braid would be. However it’s composed of carbon particles suspended in monofilament, which can block EMI while also absorbing it. Its affect on RF has been more of a revelation in my R&D than in theory, because it’s not a typical low impedance path for RF. But like @Vmax noticed as I did, when the sleeve is tied to ground either at one end or both (in the case of Furutech NCF connectors the connector body is tied to earth so both sides are tied) - I do both, I’m not sure if Vmax is doing that too - we hear a clear improvement. Is it now a faraday cage? I suppose it would be if it was actually conductive. But it isn’t, not exactly.
I’ve been experimenting tying the sleeve and connector body and hardware to ground for a while, and it’s now standard for the Whisper Elite model. That was a no brainer with some quick A/B listening against a similar cable with the same hours.
Just one caution- don’t use the sleeving on small signal cables. Power and speaker cables, definitely. It seems to rob the sound when put on my interconnects.