They include their website: http://www.911twenty.com/
Here's part of their description of what they are selling (my emphasis):
Today history is being made as National Collector's Mint releases this Government Authorized Non-circulating Liberian legal tender September 11th Commemorative. This $20 Silver Leaf Coin-Certificate is payable like a Silver Certificate in coin-of-the-realm.
Its giant 3-1/8" inches by 7-3/8" inches size dwarfs every U.S. legal tender note in circulation
Struck in .999 Pure Silver Leaf!
Each is individually numbered!
On the front, the frosted Twin Towers stand out against a mirror-like background, much as they did in the gleaming sunlight of that fateful morning, double dated 2001-2008 with our promise - "We will never forget!"Another historic first: This Silver Leaf Coin-Certificate displays a standard $20 denomination on one side. But on the other side, it's the first time ever that two separate numbers have been used to add up to the full $20 face value - it uses 9 and 11 to commemorate the 7th anniversary of the World Trade Center tragedy.
The final issue price was to be set at $39 but during this special release, it can be yours for its face value of just $20.00!
Now, let's not forget that this is Liberian legal tender. The U.S. dollar is worth approximately 57 Liberian dollars, making the face value more like 35 cents.
Please folks, DON'T buy one. Oh, lest I forget, you can purchase a box for your "coin" for $9.95. And wait, there is shipping and handling too.