Please Check the production date under seat of the chair. Please check the cylinder by opening the mechanism box under seat before purchasing: If the Cylinder has a cable pin hook on the top of the cylinder please reference to ASIN:B0B7QTP77K. If the Cylinder has a cable plastic actuator on the top of the cylinder please reference to ASIN: B0B7QL63KY or ASIN: B0B7QKNRX2. CLASS 4 LEVEL GAS LIFT CYLINDER — This heavy duty gas lift cylinder made with high construction industry standard (BIFMA Plus Qaulity) for Herman Miller Aeron Chair cylinder, ref code 1B65LR. ADJUSTABLE HEIGHT 6 INCH — Adjustable Height 6 Inch, the fully expanded height is 16 inch, the fully compressed height is 9.9 inch. DIAMETER — small black tube diameter: 1.1″ (28mm), middle chrome tube diameter 1.3″ (33mm), outside big black column diameter: 2 (50mm). REPLACEMENT PARTS FOR HERMAN MILLER AERON CHAIR — Please check the cylinder by opening the mechanism box under seat before purchasing. If the Cylinder has a cable pin hook on the top of the cylinder that this version will workable. If the Cylinder has a cable plastic actuator on the top of the cylinder that this version won’t workable, please reference to other ASIN: B0CCHQYDVG.