The U.S. has a system whereby you can set up an account at www.stamps.com and then print stamps from your home (or office) PC. You receive these blank "stamps" on sheets which you then run through your printer and the postage is deducted from your online account. Not exactly beautiful commemoratives are they?
I may be mistaken about this, but I think Scott only lists the CVP (computer-vended postage) that was/is sold by the USPS, particularly sold by a machine in post office branches.
The image shown in the original post here is a product of stamps.com, and, unless things have changed since my Scott 2017 US Specialized was issued, these products are not listed in Scott. These are labels printed at a home or office via an account with stamps.com.
As an aside, international SOR members may start seeing more of these items specifically from stamps.com, as they have announced that they have a way to send international flats at about half the price of the new international mail package prices (the classification at which all international stamp sales are otherwise supposed to be mailed as of 21 Jan 2018).
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