It is made of 1/2" clear acrylic with a large LCD powered by 2 - 9 Volt batteries.  The display clearly shows the address of WIRED Magazine.   Here is the side view:

I mailed it from the Vallejo, CA post office where I lived at the time (Vallejo is on the San Francisco bay).

There is a small label on the left that instructs the recipient to insert a paper clip into a small hole to "activate" the artwork.  Once the small red button inside is pressed by the paper clip, the display changes to title itself.  This image holds for 5 seconds then it becomes an active artwork:

5 numbers appear on the top line of the display and coalesce into the center. Then the number drops down to the bottom line and jiggles left and right briefly before disappearing.  This process repeats a random number of times before reverting to showing the WIRED address again!

Here is a partial view of the page in the August 2000 issue: