Which 4k UHD drive?

[Darklord_ICE]

Hi,
unfortunately i bought the wrong UHD drive - a BU40N but fortunately i can still return it.
So what's the best choice for a 4k UHD drive which will work reliably with AnyDVD?
I read about the Asus BW-16D1HT but found it confusing that in the shop description there's nothing mentioned about 4K UHD .. will it be supported? External drives won't work at all?
2nd question: what's the deal about flashing / patching the drive's firmware?
What's the purpose / is it required and where does the firmware come from?
Thanks!

 

[coopervid]

English as well:

https://forum.redfox.bz/threads/guide-for-flashing-uhd-drives-for-anydvd.79023/

And these drives also work in USB enclosures but they are hard to find these days. Google "OWC Mercury Pro".