3M Black Privacy Filters utilize ingenious microlouver technology to deliver world-class effective privacy for laptops and monitors. Side views are "blacked out" from prying eyes while your screen remains clearly visible to straight-on views. 3M Black Privacy Filters fade to black starting at the 30-degree side angle, are reversible between a glossy side and glare-reducing matte and reduce 35% of blue light transmission. Diagonal Monitor Size: 21.5"; Fits Device Type: Flat Panel Monitor; Frame Type: Frameless; Mounting Details: Attachment Strips; Slide Mounts.