Abstract: The invention relates to a chair system provided with a suspended and relaxing ergonomic seat adjustable by a variable full and secured inclination and balanced by body weight only without any mechanism or locking device. Said invention also relates to a seat system which makes it possible to reach and keep all positions up to a lying position by adjusting a seat length and ergonomically maintaining a body with the aid of the body weight only without force or a mechanism and without running a risk of a rear imbalance.