This flight marks the 19th and penultimate SpaceX delivery mission for NASA under the company's first commercial cargo resupply services contract with the space agency. Of the missions flown to date, this is the eighth overall to feature a preflown Dragon and even stars the first Dragon spacecraft to ever fly more than once — a milestone achieved in 2017.
With today's successful launch, this particular Dragon capsule is on its way to deliver its third batch of supplies to the space station. (Its first trip was for CRS-4 in Sept. 2014, followed by CRS-11 in July 2017 and now CRS-19.)