This is the Viper R/C Copperhead ESC & VX4.39 3900kV 4-Pole 540 Sensorless Brushless Motor Combo. The Copperhead ESC is small and offers the smallest foot print to power ratio of all the speed controls currently on the market. The Copperhead can be used in 2WD applications with VX4 4-Pole motors, but has been optimized to perform the best with VX4R 550 class 4-Pole motors in 4WD short course trucks. It comes preloaded with 5 factory preset profiles, allowing you to easily select the profile for your driving conditions, from high speed to just learning. Plus, the Copperhead features ProGauge programmability so you can easily change the parameters of the speed control to suit your needs. Additionally, all Copperhead ESCs have factory installed high capacity bullet connectors, providing easy installation and removal for cleaning and maintenance.

The VX4 540 4-Pole Brushless motors are designed to make maximum power and torque! The VX4 motors are a great choice for high speed runs in 2WD vehicles, and have been proven to deliver the power you are looking for with the reliability you demand. Plus, the combo is complimented by Vipers 180 day limited manufacturers warranty for peace of mind.

VX4R.45 Motor Specifications:
Motor Size: 540
Shaft Diameter: 3.17mm
kV: 3900kV
Poles: 4
Sensorless: Yes