Listing is for a brand new never used super heavy duty office chair pneumatic seat height adjustment gas lift cylinder complete with all parts ready to use. It has a 4" stroke / Travel. This type of cylinder is commonly used on the Big and Tall series chairs with rating of up to 500 pounds. It's a class 5 (thicker walls) with 500n rating. (a standard pneumatic gas cylinder is a class 3 with 300n rating) The tapers on both ends are standard in the industry and replaces all brands of office chairs. The short bottom taper is designed to fit all styles of bases.