Fixed or modular sofa. Frame in double-paneled poplar and pine. Seat frame with cross-woven, coated rubber elastic straps. Padding in differentiated density polyurethane foam covered with a mat in prewashed and sterilized goose down, stitched into separate compartments. Pin and bush enabling the backrest and armrest to be unhooked from the frame to allow removal of the covers. Steel base with bronzed epoxy powder coating. Fabric or leather upholstery, both fully removable by Velcro fastenings. Modular elements are joined with hooks for assembly.