HEAVY DUTY Gas lift cylinder that holds great weights - tall center support column of the chair. Holds up to 450 lbs on most office, executive and computer chairs.Highest End Class 4 gas cylinder on market. STANDARD CYLINDER DIAMETER: Outer cylinder: 2 inches, Inner cylinder: 1.1 inches. Please confirm the measurement before ordering. SMOOTH & NOISELESS: Full 360 degree rotation, smooth and noiseless movements to all directions