A Hub liners purpose is to prevent metal (Post threads) from rubbing against metal. If it does, it will wear away metal very quickly and the metal droppings can permanently stain the floor. So, metal against metal is what a plastic hub liner prevents occurring. All manual hub liners today have a 1” hole for the threaded post.

Many hub liners become threaded in use from the threaded post pressing against the soft plastic. A new hub liner is smooth on the inside. It is not threaded! Deeply created threads in the hub liner will permit the chair to rock and or wobble. Properly installed Hub liners must fit tightly. Too tightly installed hub liners will cause swivel difficulty or binding of the threaded post. Just be certain to measure the inside diameter of the base hole where the hub liner installs.

Since most hub liner walls are 1/8” thick or less, it can be difficult or time consuming to remove without a proper TOOL.

Manual chair height hub liners will not fit gas height adjustment chairs. Gas height cylinder chair bushings are not sold separately. They are available and pre-installed as part of a column, be it 45 or 50mm.