Gas Spring for office chairs-100mm,120mm,140mm Surface: Black surface Chrome surface Other colors can be made according to your demands. Bottom: Welding or Punched bottom are available Payment: T/T: 30% deposit, 70% balance against orginal B/L copy L/C: LC at sight Delivery: 7-15 working days after receiving your deposit or original LC at sight Advantage: Service---Perfect quality control, best sales team cooperation solve your problems in time. Certificate---TUV LGA DIN4550, SGS BIFMA X5.1, ISO9001