HPI Stability Control System - Savage/Baja Adj Drift Assy The Secret Weapon For Your Drift Distance and Angle The HPI D-BOX drift assist system especially developed for RC cars helps to get the perfect drift angle. Just connect the D-BOX to a steering servo and it will powerfully assist your drift driving. The device weighing only 6.7g will change your drift world! The ultra small yaw control sensor in the D-BOX detects your machine's tail sliding and the optimized automatic counter-steering prevents your car from spinning. It comes with a gain control function to adjust counter-steering amount according to the track surface condition and your drift driving skills.