The Grazie® Collection features the world's first true ergonomic stack chair. Designed by Giancarlo Piretti, Grazie's Perfect Pivot™ is a patented frictionless mechanism that exactly mirrors natural body movement to provide the ultimate in sitting comfort. Artful and timeless, Grazie's gracefully sculpted design and ingenious function blend beautifully in any environment. Backrest assembly moves over molded slide bushings and is supported by steel coil springs. This mechanism allows the backrest to move 15 degrees about an axis of rotation that is through the hips of the sitter. Injection-molded polypropylene shells and seat liner board. 12-gauge steel underseat structure. Optional upholstery over 1" thick seat foam and ½" thick back foam.