The 9 cm (3.6 inch) [54.3 x 72 mm] measurement refers to the size of the screen protector that is compatible with a specific device. Our website sells a range of screen protectors that are designed to fit different devices, and this particular size is suitable for a specific device model. By providing this information, customers can ensure that they are purchasing the correct size screen protector for their device, which will provide optimal protection against scratches, cracks, and other types of damage.