the friction disc has two different friction materials,on the flywheel side (i think) it has the regular gray colored fiber stuff as any stock clutch has.
on the pressure plate side (again i think) it has the ceramic stuff that alot of the big rigs and agriculture tractors use.it could be the other way around,i think it is like that because the ceramic stuff is really grabbie and and ******* flywheels,if it was against the flywheel it can wear it out in a hurry.
they say that this style friction disc along with the wieghted pressure plate there is less pedal effort and ALOT more holding power,also will stand up to being slipped a little better and not chew up your flywheel
i think thats right it is a sunday morning you know