No Sags is DIFFERENT: It inserts INSIDE your cushion cover –not under it. FAR SUPERIOR to simply laying anything under your cushion because that can’t compress and improve foam firmness long term because your cushion is just sitting on top of it. No Sags is engineered to COMPRESS your remaining foam (inside) on the bottom of your zippered cushion cover for unparalleled FIRMNESS and SUPPORT like nothing else on the market. This is meant to be an alternative to replacing your foam cushion cores. Normally a sagging cushion problem develops from weakening foam cushion density not the spring deck. This durable military grade foam is perfect for providing the rigidity and cushioning properties needed on the (inside) of your cushion.