Good insulation against moisture, cold, dirt through layer structure 1.Alufolie (fabric laminated) 2. PE foam, polyester 3. Only about 4 mm thick, 30g easily. Spread 45x35 cm (45x40 cm vglw.Stuhlfläche has about), folded approx LxWxH 23x12x3 cm and adhesive Velcro closure. We have them now always 2 pieces in a backpack u. Are very satisfied.