Finding a Caster to fit the Built-in stem on your chair
Does your chair have the caster stems welded or built-in? Now one of the casters has broken and need replaced. Finding a replacement caster to fit the stem may be difficult. The caster-end of the stem can differ significantly from one model to the next and from one manufacturer to the next.
Compare your dimensions to those in the table. Then follow the link of the stem class (such as NA01) with dimensions that are closest to yours to see what stemless casters are available that have the best chance of fitting your stem.