... 1.connected with the bottom of office chair 2.accept gas lift and spring lift 3.thickness 3.0mm,bearing more than 200kg Swivel Chair ... the bottom of office chair ,make to accept gas lift,for locking and tilting ,up and down your seat,make your chair perfect Usageoffice ... are famous both in the oversea and the domestic market,including barstool swivel plates, lift up mechanism for coffee tables, all ...