Orthopedic chairs use a free-float swivel mechanism that allows separate, or independent control of the seat and backrest. By independently controlling the angles between the backrest and the seat, orthopedic chairs may alleviate, and even rehabilitate, certain medical preconditions, specifically musculoskeletal issues of the spine. Medical professionals often endorse orthopedic office chairs. The Wellback 300 also has dual density seat foam which adds a new level of comfort and support. A 5-year warranty and 120kg weight rating is standard with the Wellback 300 orthopedic chair.