Listing is for a brand new never used CLASS 4 WITH 400N, office chair seat height adjustment pneumatic gas lift cylinder. 6.0 stroke (seat travel from lowest to highest seatings). Exceeds ANSI/BIFMA5.1-2011 standards, based on the specs of this cylinder, it’s load capacity is 350 pounds. Cylinder Diameter: 28mm (1.1″) Column Diameter: 50mm (approx 2″). Cylinder for Size A, B and C Aeron Chair.