The X-Chair is the most comfortable, ergonomic office chair we could find! I have had back issues for years, and I absolutely love the Dynamic Variable Lumbar support that separates the X-Chair from competitors. Not just a bar in your back, but a support that moves with you and meets you where you need it. X-Chair is also the only chair we have worked with that has seat depth adjustment to create a perfect sitting position. With Four Dimensional Armrests and height adjustable backrests, the X-Chairs are truly the most customizable and comfortable office chairs out there!