Top positive review
64GB R/W up to 100/ 80MB/s Superior Micro SDXC UHS-I (U3), V30 4K A2 - Not just good for the price
Reviewed in the United States on February 6, 2020
Not A2 random read/write speeds, screenshot from the app Cross Platfrom (no that's not a typo) Disk Test. Maybe the testing was different because I selected to use it as internal storage, have no idea. Good for the price but I wonder if an A1 rated SanDisk would have the same performance.
2/13/20 EDIT: Just tested an A1 SanDisk Micro SD and the random read/write speeds were each about 1 MB/s slower than this one, so maybe they're slower across the board. Maybe unless it's "Superior Pro" or "Extreme Pro" in SanDisk's case.