12T 550 Motor has a 30% longer armature than a standard 540 size motor for extreme monster torque, 3.175mm output shaft, Input voltage: 6-8.4V (Lipo&Nimh), 【Note: not compatible with 3S lipo battery】 OGUNKE RC 12T 550 motor is designed for incredible mod-motor power output with virtually maintenance-free operation, and long-lasting performance. smoothness for best reliability and maximum 22500 RPM OGUNKE RC 12T 550 motor’s integrated cooling fan pulls cool air through the motor to keep temperatures down. A cooler running motor allows faster speeds, longer runtime, and extended motor life OGUNKE RC 12T 550 motor’s integrated cooling fan pulls cool air through the motor to keep temperatures down. A cooler running motor allows faster speeds, longer runtime, and extended motor life 550 12T Mot.