USPS Philatelic Collector Envelopes - Great for stamp collectors or hobbyists!  This set contains three envelopes: 

-Superbowl XXX Collector's Envelope 1996 - Pittsburgh Steelers vs. Dallas Cowboys.   1 of 30,000 printed. 

-World Series Collector's Envelope 2001 World Series Champions New York Yankees.

-Phoenix Open Collector's Envelope 1999 - Phoenix Open Tournament Players Club of Scottsdale.