fold down sofa bed, folding sofa bed, sofa cum bed 1. ... materia 2.Easy to assemble&maintain 3.Function 4.OEM fold down sofa bed, folding sofa bed, sofa cum bed REASONABLE ... frame. Undergone anti-worm and humidity control between 12-15%, S shape spring , paper wire , plastic net, webbing ,lining, ect. 2 ...