Front-opening mechanism through rotation of the backrest with only one movement. The bed can be opened without removing the cover. The mechanism is equipped with a bayonet basket that allows to fix the backrests and the armrests to the mechanism. Several models of armrests and backrests can be assembled and dismantled separately from the mechanism. The bed base can be electrowelded or provided with slats or large slats. The seats of all models are provided with elastic straps. A 18cm-thick mattress can be used on models 710 Magnum.