Natural materials are well known for their longevity and on average last around three times longer than synthetic duvets. Environmentally friendly choice as they are a by-product of the food industry and are biodegradable. Down feather is full of tiny pockets that can trap in the air and provide an insulation-like feel, maintaining warmth. Because of the insulating feel, many down duvets, therefore, require less filling in order to reach a high tog rating, allowing down duvets to be of a lighter nature if preferred. If you suffer from allergies, microfibre filling may be more suitable for your needs.