PF18.1 fits standard desktop LCD monitors with a viewing area diagonal of 18.1 inch actual filter dimensions are 11.30 x 14.13 inches. This filter is designed for Non widescreen desktop LCD monitors with screens that appear more square than rectangular and have a 4 x 3 aspect ratio. 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.