This micro SDXC card has a decent speed for most 4K recordings as it has a write speed of up to 31mb/s and read speed of up to 44mb/s. That said, camera settings such as frame per second and bitrate can affect this. In my case it was able to record 4K @ 30FPS and 1080p @ 60FPS without any issue. Usually if a card is slow or not up to the standard my GoPro stops in the middle of recording but that never happened with this one. I ran speed test on this card as well with different file sizes as I always do when I get a card to make sure it's not fake and that it provides my needed read/write speed.
Scrolling through amazon finding a memory card for my action camera, and came across this one, it was cheaper than the sandisk brand, the actual storage reads 58.6 GB on my go pro, its slightly less than the advertised, later on i read, the excessive storage is used, in case you format the memory card, and want to restore your old data so ill settle with 58GB in case of some mishap happen and i need to restore old files, overall it works so far