Classic slatted frames have an arched tension. The disadvantage is that you have an incline on one side and a decline on the other. The slats are anchored on the outside and then arched over. The idea is that the sleepers exert pressure on the slats with their weight and thus lie straight. But the problems are that if you’re light, you can’t press the slats flat, and if you're heavy, you sag! Who among us is standard?
A Hüsler sleep system is not just a slatted frame. The combination of the stable frame inserts or comfort frame and spring element ensures that even heavy people never sag down into the bed. Conversely, light people have the advantage of not lying on an arch but can lie straight as well.