Features: Includes a 360 degree swivel plate attached to a dual wheel roller system. 16mm two-hole, metal, flange-mounted ball bearing rests on individual support bearings and is perfect for most industrial transfer applications. The ball transfer unit can also be used in a variety of non-industrial applications, including retail store displays and airport baggage transfers. The ball support cup is hardened and plated, the protective cover ensures low torque and long service life. The ball transfer unit is the perfect replacement for your broken unit on your office chair. Specifications: Model Number: -15A Type: Window Rollers Treatment: Zinc Plating Model: -15A, 5/8-A Length: 50mm Width: 30mm Height: 2mm Hole Pitch: 40mm Mounting Hole Distance: 4mm Ball Diameter: 15.875mm (5/8 inch) Single Load: 10kg (Max. 20kg) Single Weight: 43g Color: Silver Material: Steel Package Contents: 20 * Ball Transfer Unit Only the above package content, other products are not included. Note: Light