Flexi slats are used in steel sofa bed and bed frames of all sizes.
A flexi slat is steam bent Beech wood. Several layers are slowly curved and as a result they are extremely strong.
Consequently when two bodies of unequal weight are lying together the slats will flex and therefore distribute the weight evenly.
The slats vary in length and also width.
Almost unbreakable they often have life time guarantees from suppliers as they are inexpensive to manufacture.
The slats are held in position by plastic caps at each end. This also helps the tension held in the curved Beech wood.