PF20.1 fits standard size LCD desktop 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 monitors with screens that appear more square than rectangular and have a 4 x 3 aspect ratio. Helps keep confidential and private information safe in open cubicle offices. 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. Excellent for high traffic areas. Reversible for either glossy or matte screen finish. Reduces reflections when used with the matte side facing you. Helps to protect your LCD panel from scratches and abrasions. Easy on easy off attachment system.