Many 4K video cameras require a Class 10, U3 - Read Speed of 90 MB/s & Write Speed of 80 MB/s.
I tried one of these super fast 90 MB/s cards in the TYPHOON H, works well but not necessary as the camera does not produce large files at high bit rates. This means that if you buy a 16, 32, 64 or 128 GB micro SD, you don't have to invest in a super fast card. Anything with a write speed above 40 MB/s should work.
I'm with PatR. I like to have a lot of cards floating around to ensure that I don't end up somewhere without one. It's the detail I'm most likely to overlook when I'm in a hurry. The 64GB size seems to balance capacity and price better than any other.
I've been using a Samsung 128 GB card in my H.
The ST16 ( last time I checked ) will not accept that as it has to be formatted in FAT32.
I have had problems with my Samsung card saving corrupted files or even completely failing to save pictures and movies.
After research on this forum and then on the internet I've just ordered a 64GB ( V60 speed ) card.
I don't think a massive card is needed.
A whole day's shooting get's corrupted or lost if the drone goes down in the sea.
Smaller cards would mean you at least have the images. ( we hope )
Video files do not become corrupted unless you forget to stop the video. If you start a video and shut down the H without first stopping the video it will be corrupt every time. You must push the record button twice for each video. Once to start and once to stop.