A shoulder- and/or neck-holder, seat-belt, seat and sets of vibration-dampening energy-absorbers are integrated into an energy-absorbing, vibration-dampening safety-seat in order to restrain the shoulders and/or neck of a belted passenger, dampen vibrations and gradually absorb subenergies, resulting from a subdivision of the total energy, just below the respective injury-irrelevant threshold-values in any real-world accident of a transport-system, submarining or during in-flight turbulence. The conversion of an adult-seat into a child-seat or a baby-cot or vice-versa is simple. A rotatable device makes the holder easy to use.