How durable is this mattress over time?

Built to last, scoring 7.2 on durability with a 10-year warranty. It pairs CertiPUR-US certified high-density foam against 1000 pocketed coils of thick 13.75-gauge tempered steel, which resists sag far better than lighter-gauge springs and holds its loft against body impressions. The rating reflects that a deep 4-inch plush comfort section carries more foam to soften gradually over years, but the tempered-steel core beneath is built to go the distance. Rotating it periodically helps it wear evenly.