Sobella Down Alternative Hotel & Resort Duvet Insert Bedding with Medium Warmth for All Season Comfort Available in Cal King This box-stitch duvet insert is a cozy addition to any bedding ensemble. Down alternative gel-fiber fill gives wonderful loft at an affordable price. 210 thread count exterior shell for a superior feel. Hypo-Allergenic and Machine Washable (tumble dry low) Trusted by Luxury Hotels around the world.