The 43.9 cm (17.3 inch) [383 x 215 mm] measurement refers to the size of the screen that our website sells screen protectors for. This size is commonly found in laptops and notebooks, and our range of screen protectors is designed to fit this specific size perfectly. 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, smudges, and other types of damage. Our website offers a variety of screen protectors for this size, including tempered glass, anti-glare, and privacy options, so customers can choose the one that best suits their needs.