Nikwax Down Proof is a washing machine-applied waterproofing treatment for all down clothing, sleeping bags and down duvets/comforters. Features: - Restores water-repellency to down and shell fabrics of down filled clothing and sleeping bags. - Ideal for all down garments, sleeping bags and down comforters. - Adds water-repellency and revives breathability - Nikwax Waterproofing is the international leader in water-based cleaning and waterproofing solutions for clothing, footwear and equipment.