ISO 8139:2009 specifies the mounting dimensions required for interchangeability of rod-end spherical eyes of pneumatic cylinders. The rod-end spherical eyes have been designed specifically for use with 1 000 kPa (10 bar) series cylinders manufactured in accordance with ISO 6430, ISO 6432 and ISO 15552, but this does not limit their application. The spherical bearing end eyes are used on piston rods of pneumatic cylinders for mechanically transmitting the cylinder force under oscillatory rotational and tilting movements. The design of the rod-end spherical eyes is based on the maximum forces resulting from the specified internal diameter of the cylinders and pressure according to ISO 6430, ISO 6432 and ISO 15552.