Schellenberg ball bearings (23 mm for maxi systems = belt width) The Schellenberg ball bearings are for octagon tubes with a diameter 60-70 mm. The two ball bearings supplied can be integrated quickly into your Maxi-shutter system. They are easy to install and have a diameter of 40 mm. Used for Maxi systems. Dimensions: Diameter: 40 mm octagonal tubes (Ø 60-70 mm) Easy installation Contents: 2 pieces