http://cyclepathnw.com/2014/03/mavic-cosmic-carbone-40-c-wheel-demo-starts-now/


Pictured above is a cross section of the rim. 

You can see a small aluminum insert that the nipple threads into, the aluminum rim that helps dissipate heat energy  from the brake track, and the foam core that presumably aids in rim construction and reduces the road noise typically found in carbon road rims.




'아마도' 림 조립할때 도움이 되고 카본림 특유의 소음을 줄여준덴다