Furutech has released a diagram of the inside, you can see it here:
It is not a conventional parallel power conditioner using reactive elements like capacitors. Nevertheless, I have had a few customers with AC power quality measuring devices report back to me substantial reduction in noise by using NCF parts. In my experience, the 1st NCF parts you put in a system make the largest difference and I would suggest the GTX NCF receptacles as being the best bang for the buck. Further NCF parts do help but the effect is cumulative, and the 1st parts added reduce noise the most, additional parts still reduce noise but not as much. NCF parts are also generally the highest quality, so besides the NCF material you also get the highest quality copper, plating and general construction quality possible, so the parts are usually a large improvement over others in many ways, not just because of the NCF material used.
So, if you have good quality AC power and a lot of other NCF parts the effect of the Clear Line may be negligible. OTOH, if you have some noise and currently use no NCF parts, the Clear Line may make a large difference.
I have a few on the way but have not received my order yet. My system uses all NCF plugs, IEC inlets and receptacles, so I'm not sure how much, if any, adding a Clear Line will improve my own system, but I'll report back when I get them.