15 tog Deep Winter A very warm duvet, perfect for the coldest winter nights or for individuals who easily feel the cold. Hollowfibre is a type of filling. Its name comes from its unique structure: each individual strand of polyester is spun with a hollow channel or core running through the centre, similar to a very fine, hollow straw. Enjoy a sneeze-free, breathable night's sleep. Plus, it’s machine washable for easy, long-term hygiene and freshness.