friction surface, the pads slightly hangs off the edge of the rotor so there is a slight section that doesnt touch the rotor causing a un worn lip on the pad.
I been told this is not a problem, but its still something to consider.
If you want to keep stock wheels as a fitment option i suggest the MWS or Ztuner brake kit as it fits inside of stock wheels.
Member # 54233 and The 4th Z32 Project.....Its time to do it all over again...