3M Privacy Computer Filter PF400XXL 19 - 21", flat frame, keeps confidential information private with 3M's patented microlouver technology; on-screen data is visible only to persons directly in front of the monitor, passersby see a blank, dark screen. It offers privacy without blurring or distorting screen images. It reduces glare up to 95%; prevents static and dust build-up when properly grounded; blocks up to 99.9% of ELF/VLF E-field radiation when properly grounded; utilizes the assembly-free flat frame design; outside dimensions: 14.33 x 17.33 x 0.40 inches (364 x 440 x 10.2 mm); viewing area diagonal is 20.6 inches (523 mm); standard tint glass; cleans easily with a soft, lint-free cloth and glass cleaner.