This is a set of six cards, in a very sturdy cardboard box that almost feels like wood.  Our scan shows the front of the box; see 20308789B for sample cards.  It’s Hongkong Post’s “Postage Prepaid Picture Card Series No. 57,” and each card has pre-printed, coloured, global postage and a special first-day-of-issue (14 November 2017) postmark.  Our other scan shows you the examples of how one front and one reverse look, but of course all six cards are different within a similar theme.  Grade: 1