The Circular Displays (Diameter: 40 mm) refers to a specific type of smartwatch or fitness tracker that features a circular display with a diameter of 40 mm. Our website sells a range of screen protectors that are specifically designed to fit and protect these circular displays. These screen protectors are made from high-quality materials that are scratch-resistant, shatterproof, and easy to install. By using our screen protectors, customers can ensure that their circular displays remain in pristine condition and are protected from everyday wear and tear.