Superior Material: The 550 21 T brushed motor featured premium quality materials with high strength magnets for better and more stable performance, ensures long service life | High Performance: Size 550, Powerful motor has a 30% longer armature than a standard 540 size motor for extreme monster torque. Unlike other 550 Motor and 60 A ESC Combo sold on the market, we adopt a 80 A ESC replacing 60 A ESC to better solve the overcurrent and overload problem of the ESC | Copper Windings and Bearings: The high purity copper windings and sealed bearings are durable, with low friction and low noise | Come with an Extra Heatsink Cooling Fan: Besides the heatsink built in the 550 motor itself, we provide an extra heatsink cooling fan in the combo to better solve the overheat problem of the motor | Wild Application: We provide two combos 21 T motor / 21 T motor and 80 A ESC to choose from, which is perfectly compatible with 1/10 RC Off-Road Car for TRAXXAS TRX4 TRX6 TRX4 Bronco Pro Axial SCX10 SCX10II AXI03007 JL 90046 RC4WD D90