These screen protectors may not be the cheapest, but they are worth their money. With the included lint-free cloth can be removed (in combination with breathing on) good existing dust and grease. The manual describes well how the films are to be attached and this works very easy. Also, remove any dust particles that can reach between screen and film, despite all precautions, works well with scotch tape. Very positive: the display quality and the touch screen sensitivity suffer a bit. Personally, I find the gliding the stylus on the film surface very pleasant, he now slides with a very slight resistance on the screen, which in some games will help to guide the stylus more precisely.
The film for the touch screen is in fact not 100% fit, especially in width missing about 0.5mm. That bothers however - especially at center type application of the film - not in the least.
Overall, the films serve their purpose very well. Here you can access calm.