Hill Descent Assist significantly increases safety and performance when towing down hills. All proportional brake controllers use inertia to determine the braking force applied to the brakes. The firmer the braking the more inertia is generated and braking is applied on the caravan or trailer in proportion. However, when descending steep hills the driver of the tow vehicle typically feathers the brakes to maintain speed - this generates no inertia as there is no deceleration. As a result there is no braking applied to the caravan or trailer and the tow vehicle is being pushed down the hill by the caravan or trailer. WiTi Hill Descent Assist eliminates this by measuring the angle of descent and applying the brakes relative to the gain setting displayed on the LCD screen. The steeper the descent the more braking is applied resulting in a safer more controlled descent.No other brake controller offers Hill Descent Assist - another global innovation for WiTi.