office chair parts with two-type for armrests, non-synchro & synchro mechanism for choice, three colors for the plastic 1)Staff chair with non-synchro & synchro mechanism, two armrests PC-28 & KP-08 for choice;2)With black, grey and yellow color for plastic for choice;3)Fabric color diversity for choice as you like.4)Gas-lift chair, can be up and down, PP base.