This unused set is Hongkong Post’s “Postage Prepaid Picture Card Series No. 52,” with pre-printed postage corresponding to the photos, and all with 17 March 2015 first day of issue postmarks.  These are 3D cards.  Our scan shows two of the fronts and one of the reverses, for your reference, but there are seven different cards in each set, and four sets are available.  By the way, these are really sturdy and quite heavy.  Grades: 1