Danovel Feather Sandwich™ is a special combination of duck down feather wrapped over a foam core. Danovel has a unique trademarked way of ensuring the best comfort without making the seat too soft. Its interchangeable center foam core allow you to replace it or the feather down mix easily. And of course there isn’t a need to change the foam core as Danovel uses a quality material which is Non-Sag Foam.