Privacy filter is designed for use with your 21-1/2" laptop or flat panel monitors. PrivaScreen Technology darkens screen image when viewed from a 30-degree side angle to prevent prying eyes from reading your screen. On-screen data is only visible to users directly in front of monitors. Recyclable filter protects monitor screens from dust, fingerprints and scratches. Anti-reflective surface reduces screen glare to help prevent eyestrain. Screen is easy to attach and remove with built-in tabs. Screen size should be taken by diagonal measurement.