Engineered hardwood frame with mortise & tenon joinery. All wood is kiln dried for added durability. Lumbar pillows and throw pillows included. High-gauge sinuous springs provide cushion support. Seat cushions: Fiber-wrapped high-density polyurethane foam. Seat firmness: Soft. On a scale from 1 to 5 (5 being firmest), it's a 1. Back cushions: 50% polyester fiber, 45% duck feather and 5% duck down in down-proof ticking. Loose, reversible cushions with zip-off covers. Sectional pieces attach via alligator clips (included). Modular pieces are easy to move and can be used standalone or added on to later. To see the full assortment of potential add-on pieces, see the Harmony Modular Collection page. Assembled in the USA.