Heavy Duty Cylinder Fits Herman Miller Classic Aeron Chair as Replacement SHS. Listing is for a brand new never used CLASS 4 WITH 350N, office chair seat height adjustment pneumatic gas lift cylinder complete with all parts ready to use. The black color of the spindle is made of hardened steel that was heat treated, which turned the color to black. Based on the specs of this cylinder, it’s load capacity is 350 pounds. 4.5 stroke (seat travel from lowest to highest settings). Gas spring diameter 1.1. Support column is 2 in diameter. Dimensions when fully compressed. The chair not included. When you received your package, promptly check the items to make sure the items are intact.