@
mitch13 - your profile has 'Appraising the market', so I assume you are considering Kindle but don't actually own one yet, I would think all current Kindle devices accept AZW3. The calibre Polish Book feature can inject a book jacket into an AZW3 file.
And, there are some useful Kindle related tips in this post from jhowell ==>>
https://www.mobileread.com/forums/sh...98#post3551898
BR