Most extensive chair parts replacement catalog online

Matte Black 5 leg 26" metal base complete kit Adjustable Height Swivel & Rock

Style # SKU K7223G-3318

26” diameter.
Over 2 1/2"± adjustable height.
Rock and swivel mechanism 6"X10" bolt holes.
Seat plate swivel attaches flat or round chair seats.
Includes class 3 gas cylinder. Low range height of 12 1/2" to 15"± high. 
Includes 5 larger 2 3/8’ matte black hooded casters roll better on wood or carpet flooring.
Everything Matte Black!*(of a color, paint, or surface) dull and flat; without a shine)

$190.30

Rock and Swivel 3318G version: Floor to top of mechanism with casters, base, gas cylinder, and swivel tilt mechanism-Low is 13 1/4", high is 15 3/4". 

Insert without tools the black gas cylinder into the center hole of the 5 leg chair base. Just sitting in the chair more than once will make it extremely tight and difficult to remove without tools.