Most innerspring mattresses are built with a single base layer of coils, covered by foam, fabric, or other padding. Coil-on-coil mattresses like the Saatva Classic, on the other hand, have two layers of coils. On top of the support core is a thinner, more flexible layer of individually wrapped comfort coils. (See the details of our construction.)
Coil-on-coil construction has a couple of advantages. First, dual-coil systems are more durable and less likely to sag over time. Second, the extra layer of contouring coils provides added pressure relief and targeted support where you need it most, for a comfortable, supportive night's sleep.