PF20.1 fits standard size LCD desktop LCD monitors with a diagonally measured 20.1" viewable screen; actual filter dimensions are 16.12" high x 12.1" wide. This filter is designed for desktop LCD monitors with screens that appear more square than rectangular and have a 4 x 3 aspect ratioe. Notebook privacy filters keep confidential and private information private. Utilizes 3M(TM)"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.