To be precise, this is Hongkong Post’s “Postage Prepaid Picture Card Series No. 51” and is a set of seven unused cards issued on 17 June 2014; the scan only shows one.  We now have five sets available, and all are Grade: 1.  One set has no postmarks ($14).  Two sets have a first-day “G.P.O.” postmark ($16), and two sets have a special pictorial “Hong Kong Museums Collection” postmark ($18).