Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Effective

I use this on a MaBook 13.3 (you must order the 13.3 WIDESCREEN version). It fits perfectly, the tabs to keep it in place are quite unobtrusive. It diminishes brightness of the screen. It will effectively protect your privacy if the viewing angle is more than aprox. 30 degrees from the screen. You can have a glossy or matte finish using one side or the other of the screen.