Heat regulated and extremely lightweight this quallofil air 4 seasons double duvet will keep you comfortable all night longsynthetic 4 seasons double duvet a 175 gm duvet for the summer and another 300 gm duvet for in between seasons join the two together to form the winter duvet fasten with ties quality value for its filling made up exclusively of extra fine silicon hollowfibres ultra plump and ultra lightweight 100 polyester allowing better circulation of air and reducing