Despite the out of date phone on Monoprice's website (it shows NAS 2.0 drive), I received a current NAS 3.0 drive. The drive was originally designated for Canada and I'm in USA, so it shows up as "Out of Region" when I register on WD's Support Portal; but I called and they confirmed it was fully under warranty for the full 3 years.
Details: Model = WD40EFRX-68N32N0 (this is latest version) Firmware =82.00A82 Build Date = 14-Feb-2019 WDIDLE3 /R shows 300 seconds (correct setting for a Red)
Super easy install. Just take it out of the bag and pop it into the synology 1515+, then login to the synology and added it as a hot-spare to my existing volume. Of course, I'm not sure how it will hold up over time but my other WD drives have been spinning for 7.5 years so I think it will be fine.