It seems that every manufacturer and seller has their own version of part names and key letter references. The simple drawing above  shows some common terms of what may be referred to on our website for novice purchasing, installation or removal. 

Letter V part shown in red is commonly called a Column. Each purchase of a COM type cylinder is supplied with a 50mm (2“ OD) outside diameter column. The column is NOT the gas cylinder. The columns purpose is to support the encased 1” cylinder in an upright position during rocking, leaning or swiveling. The column is probably a slightly different size than your original but yet will still function and fit perfectly. 50mm (2”) diameter columns are the most common size and are measured at their widest end.

Letter A - Not shown. Make sure cylinder hole at top of part V is about 1” diameter. (Most are 1”.)

Letter V - Make certain column V is 2” diameter and not 45mm (1 3/4”) diameter. (We do have some 1 3/4” columns available.)

Letter S - Is the only measurement needed by us for new replacement cylinder purchases. 

To measure select either option:
     1. Remove bottom clip and washer from underside bottom of column V, then hand pull column V off and add about 1" to the cylinder measurement. Precision not needed. (1” is the approximate amount still captured within the mechanism.)
     2. Lower chair seat to lowest position and measure entire column V up to the mechanism and add 1”. Precision not needed. (1” is the approximate amount still captured within the mechanism.)

Answers to commonly asked questions
• The white or colored plastic button at the cyinder top should not be removed nor activated.
• The amount of height travel (stroke) is relative to the maximum cylinder height “L". i.e. a short cylinder equals a short stroke.
• Column plastic top Bushings are not available. All our replacement columns contain a new bushing.
• The diameter of the column protruding out the bottom of the leg base is unimportant.
• Buy or rent a cylinder removal tool (Lift Off) or a 15” length or longer (Plumbers) pipe wrench which will be required to remove a cylinder from the mechanism bolted to under the seat.
• A vice grip pliers won’t work to remove a cylinder.
• No tools needed to install the cylinder.
• Is your cylinder obsolete?
• All diameters provided are (OD) outside diameter.

We have 3 short videos concerning gas cylinders. We highly recommend you watch them.

Watch our 3 topic Video installation. Click on SELF HELP VIDEOS near the top of our website page.
     1. Measure chair gas cylinder for replacement/remove
     2. Remove gas cylinder using a pipe wrench or Lift Off tool
     3. Gas Column/Cylinder removal from 5 leg base 

Below drawing is only as a courtesy for the curious..........