A very high percentage of car passengers do not pay attention to the regulation of the headrest. This security element is able to prevent neck injuries, which are currently the leading cause of claims for damages against insurance companies, giving an idea of ​​the magnitude of this type of injury. Many of these accidents are creep life-long consequences, usually evolve worse as you get older.
Neck injuries may occur either after suffering a frontal collision, during which the body of the occupants, due to impact, following an initial forward movement begin to move backwards until the back of seat and headrest finally stops them
Contrary to what many people believe, the "whiplash", named generically to many of these injuries, is typical of rear-end collisions at low speeds in urban traffic and also mid- high speed.
To prevent injuries the headrest must be set as follows:

1. Horizontally, the driver’s or passenger’s head should be close to the head restraint, so in case of collision it will work as soon as possible, it shouldn’t be a space of more than 4 inches.
2. As for the vertical adjustment, the general recommendation is that the top of the head restraint be positioned at the same level as the passenger's eyes. In other words, the bulk of the head restraint is directly in line with the passenger's ears.
When buying a vehicle, whether new or second hand, pay no attention only to the engine or painting, also make sure that the headrest can be adjusted appropriately, depending on your height and riding position.
Highway Safety estimates that up to 90% of vehicles have their head restraints positioned incorrectly. A properly positioned head restraint will minimize neck injury in a crash, especially from a rear-end collision.