Dinesh, Contact Posturite (a web search will find this for you). The chairs are not cheap but you will get a free assessment of your requirements by a trained ergonomist. I now have eight people on their chairs (The RH range) and they are superb for long durations and have resolved the back symptoms that were the cause of calling in Posturite in the first place. Typing this sat in my v. comfy Posturite chair... Regards, Richard