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 fer applications. Ball fer unit can also be used in a variety of non-industrial applications, including retail store displays and airport luggage fers. Ball support cup is hardened and plated, protective cover assures low torque and . Ball fer Unit is perfect replacement for your broken one 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 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: 10 * Ball fer Unit Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.