10MM OR 11MM - Our PVC coated casters are available in two sizes.Therefore, please determine the required pin size to the nearest millimeter.90% require 11 mm, except, for example, office chairs from the Swedish furniture manufacturer.HARD BRAKING - To prevent unintentional rolling, the chair with mounted hard floor castors only rolls under load.Perfect in the office, at the table and for games.MAXIMUM PROTECTION - With the 50mm castors for office chairs you can move flexibly and protect surfaces such as parquet, laminate, tiles, carpet or stone floors thanks to the soft PVC coating.The two wheels on the steel axle ensure comfortable rolling.The sturdy plastic housing sits above and, together with the bar, ensures a stable connection to your chair.If you encounter any problems during use, please feel free to contact us