This is the HPI D-Box 2 Adjustable Stability Control System for Off-Road and On-Road Vehicles.
The HPI D-BOX 2 was designed for all types of RC cars, it's not just for drifters! Use the D-BOX 2 on slippery surfaces like wet muddy conditions, paved surfaces, wet clay and loose dirt tracks to give you the most control while you turn. All you need to do is simply connect the super-small D-BOX 2 between your receiver and steering servo for an amazing difference in your driving performance!
The D-BOX 2 is the perfect item to help you get the perfect drift angle and long drift distances, for a drastic improvement to your drift driving! Just change the Sensitivity Mode Switch to help alter your car's angle through the turns. Includes: One HIP D-Box 2 Adjustable Stability Control System