The castors in the set are specially designed for Topstar office chairs and do not fit the Swopper Aeris. They are suitable for hard floors such as wood, parquet, tiles or stone and are compatible with certain Topstar models, e.g. "Open Base", "Open Art", "New Workart", "Sitness 50", "Wellpoint SY", "Syncro Net", "Syncro Soft" and "Lady Sitness Deluxe".