Tech brief; 3M Privacy Filter

Quick look

Security filter for monitors

Price: $62.95 for 15'inch

Phone: 800-451-7592


Wireless portals are nearly ubiquitous these days. They've expanded from coffee shops and airports to restaurants and even some bars. But even with WiFi security and high-level encryption, you're still vulnerable to the common interloper who pretends to read the paper beside you when he's actually reading your computer screen.

What's worse: With modern digital cameras and cell phone-camera hybrids, people could take snapshots of your screen without you even noticing.

Secure-It Inc. of East Longmeadow, Mass., sells a filter that attaches to your computer monitor, letting only a user seated directly in front of the screen view the image.

The 3M Privacy Filter fits any CRT or LCD screen and blocks ambient light in a fashion similar to vertical blinds, narrowing the viewing angle to straight ahead.

It took mere seconds to install it on my notebook PC. I simply attached small pegs on the corners of the monitor and slid on the privacy filter.

I used the notebook in various settings and had no problem seeing the data while seated in front of the unit, regardless of the light. But I got a lot of attention from passersby who thought I was typing vigorously into a powered-off notebook.

A waiter even told me that my computer was off. When I told him about the filter, he pointed out its weak spot: Because the protective screen uses vertical blinds, people looking down on the screen can see the data.

On the plus side, the filter also alleviates eyestrain by reducing glare. But I don't recommend it if you do a lot of graphics work that entails color correction or photo editing, because the filter makes it harder to judge color accuracy.

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