Features: Features a 360 degree swivel mounting plate attached to a double wheel roller system. Two-Hole, metal and Flange-mounted 16mm ball bearing resting on individual support bearings and is Perfect for most industrial transfer applications. Ball transfer unit can also be used in a variety of non-industrial applications, including retail store displays and airport luggage transfers. Ball support cup is hardened and plated, protective cover assures low torque and longevity. Ball Transfer Unit is perfect replacement for your broken one on your office chair. Specifications: Model Number: CY-15A Type: Window Rollers Surface treatment : Zinc Plating Model : CY-15A ,5/8-A Length : 50mm Width : 30mm Height : 2mm Mounting Hole Pitch : 40mm Fixing Hole Distance : 4mm Ball Diameter : 15.875mm (5/8 inch) Single Load : 10kg (Max. 20kg) Single Weight : 43g Color: Silver Material: carbon steel Package Contents: 40 * Ball Transfer Unit