STRUCTURE Spring system: 175 dual-cone springs (single version) made from 2.2 mm steel wire. INSULATION Insulation by means of thermofused, needle-punched, highly flexible, 100% polyester white felt. Double layer of undeformable, CFC free, eco-friendly polyurethane foam with boxed border system. FILLING Winter side filling in Pure Merinos Virgin Wool, mothproofed, needle punched to prevent sagging. Summer side with ARIA filling in breathable polyester and fresh white cotton. Protective sheet in high-strength NWF to secure the quilting stitches. FABRICS One variant in viscose rayon and cotton.