... material ( import from korea ) 2) Sries: 550 ,540,750,280 micro-motor brush 3) by good conduactivity,grindability... Details of bruehes ... carbon power . 2) With good condactivity ,grindability,inverting... 3) Every micro contact point be made by the auto machine.... 4) Various ... of micro-motor brushes suit for 550,540,750,280 motors. 5) according per ...