PureTek Roll-On protects iPhone 4/S models from dust and air bubbles. The film automatically aligns with the edges of the screen and rolls down the face. The system is only available for iPhone 4 and S models, but Android and WP7 users will have to keep applying the film manually. It even includes a free replacement if you somehow manage to screw up the first time and get it right, the system is available for $20 from the company’s website. It currently only covers iPhone 4S models, and Android users must apply it manually.”]
Source: https://gizmodo.com/how-to-apply-a-dust-free-screen-protector-even-if-you-d-5875030