With 5 Casters And A Bottom Plate Stand Cylinder, This 28-Inch Nylon, Ready. [Durable nylon base] The base is made of high-quality nylon, which is stronger and more stable than metal and plastic. Load-bearing capacity up to 500lbs. Durable nylon material provides a strong chair base [Heavy duty Bottom plate] Gaming office chair tilt mechanism mounting hole spacing: 10" * 6". Turn the handwheel to tighten or loosen the rear tilt tension. [4.9" stroke cylinder] The gas lift cylinder (Class 3) length is 278mm and the extension length is 403mm. Stroke 125mm (4.9inch). [Smooth and quiet rolling casters] This office caster has precision ball bearings to provide smooth and quiet movement, and the steel structure is durable. Universal size: 1122mm. [Warranty] If there is any problem with the computer chair base, please contact us in time. We will provide free replacement or full refund.