Seat and back cushions should have the same quality of foam (Everflex, Duraflex, or Econoflex), but should have different firmness. Back cushions should generally be softer (less firm) than seat cushions, since they don’t support your full body weight like seat cushions. For cushions in high-use areas, we recommend our 20-year Everflex, while for low-use cushions (in a guest room or low-traffic area of your home) Econoflex grade should be fine. The firmness of your foam should depend on the comfort level you desire, as well as the thickness of the cushion. The thinner the cushion, the more firm the foam should be to provide adequate support for seating or resting your back. Contact our friendly Customer Service agents with any questions about selecting and ordering the right foam.