The NECK-PRO head restraints are linked to an electronic control unit: if the sensor system detects a rear-end collision of a predefined degree of severity, it releases pre-tensioned springs inside the head restraints, causing the latter to move forwards by 40 millimetres and upwards by 30 millimetres in a split-second; this has the effect of providing support for the heads of front seat occupants at an early stage. In this way, Mercedes-Benz has improved the level of protection for the occupants in a rear-end collision and reduced the risk of whiplash injuries.

Following the deployment of NECK-PRO, the head restraints can be released using a special tool provided with the car, and can then be pushed back manually to their original positions.