Office chairs basically comes in 3 sizes, first is small backrest chair the second is medium backrest chair which comes up to the shoulders and third is with head support chair. Once you decide the size then you can consider the price factors. The amount you invest will definitely reflect in quality of product. Features like fixed armrest, 2D armrest or 3d armrest can also be prioritized in advance. The combination of all this would help you to finalize a perfect product