Our polished aluminum office chair bases are made in the USA from durable materials and are available in two widths: 26″ and 27.5″”.  Each base has a 2″ (50mm) center hub to accommodate a 1″ gas cylinder and has five 7/16″ x 1″ (11mm x 25mm) caster sockets.  Bases can be ordered without casters or pre-assembled with either hard casters for carpeted surfaces or soft caster for hard surfaces.  Add a gas lift cylinder to your order for a complete chair base replacement.