Hobbypower 30a Brushless Speed Controller Esc for Multicopter Kk Quadrotor(pack of 4pcs) Compatible with: 400-450 helicopters / Aircraft or Quad-Rotor Multi RC Helicopter Good for quadcopter KK multi-copter Max Speed: 210,000rpm for 2 Poles BLM, 70,000rpm for 6 poles BLM, 35,000rpm for 12 poles BLM Pack of 4 pieces,search separate product via ASIN:B00XKX5TBE