Double postal cards, letter-sheet envelopes, double-letter envelopes

§ 2502. Double postal cards, letter-sheet envelopes, double-letter envelopes (a) The Postmaster General may furnish for public use, with postage stamps printed or impressed thereon, double postal cards, letter-sheet envelopes, and double-letter envelopes. (b) The Postmaster General may not make payments for royalty or patent right on any of the articles named in this section.