What makes this duvet insert different? Made in 3 weights with the finest materials to support your ideal sleep temperature: Enjoy the closest feeling to down with PrimaLoft® Luxury Down Alternative®—a premium, hypoallergenic fiber that mimics the weight and gentle loft of down. Wrapped in a soft, breathable shell, each insert has a unique bafflebox construction that keeps the fill perfectly in place to maintain fluff and shape over time. The Weight for Your Ideal Sleep Temperature Warm Sleeper or Climate – Lightweight Comfortable Sleeper or Climate – Midweight Cool Sleeper or Climate – Ultra-weight