the better ones are just a twist fit, although i ditched mine as it wouldnt stick where i wanted it on the screen due to the curve in the screen...dont actually know where it ended up....
That is nice but dear, like the outlining. I have one with the stupid little screws and lost one down the vent! Use the 'no more nails' sticky tape, it is about 1.5-2mm thick so takes in the curvature of the screen.