They ARE much less weight. And very expensive. But they should perform great.
Center is made out of steel and zinc plated, but I will make dur-alu ones as soon as I get top quality material over here, which is not so easy...
Even with steel centers, much lighter then OEM. Discs are 24 mm thick, 305 mm big. Just gave 4-pot's to friend who will work on them for me, paint them and make all needed
