Structure: kiln-dried hardwood, joints are glued, double dowelled, corner blocked and screwed/lag-bolted as necessary.
Springs: S shape springs
Foam: Different thickness high-density foam for the seat, arm, and back.
Upholstery: Fabric or leather.
The best choice is seater with leather, leather is easy to clean and impervious to stains. Back with fabric, the fabric is soft and with a huge pattern.