From the Manufacturer
Notebook privacy filters keeps confidential and private information private. Utilizes 3M's patented microlouver technology so only persons directly in front of the monitor can see the image on screen, passersby see only a blank, dark screen. Unique attachment system, stays in place even when monitor is closed. Lifetime warranty.
PF12.1 fits standard notebook computers with a diagonally measured 12.18" viewable screen; actual filter dimensions are 7.32" high x 9.74" wide. This filter is designed for non-widescreen laptop computers with screens that appear more square than rectangular and have a 4:3 aspect ratio. Notebook privacy filters keep confidential and private information private. Utilizes 3M's microlouver privacy technology so only persons directly in front of the monitor can see the image on screen; passersby see only a dark screen. 3M's PF12.1 Privacy Filter provides more effective privacy than competitive filters and offers more consistent quality and uniform appearance, thus reducing visual distractions.