Micro SD Card with Adapter,U3 A1 MicroSDXC Card 667X High Speed Up to 100MB/s UHS-I MicroSD UHS-1 Memory Card for Android Smartphone Nintendo Galaxy Fire and Gopro (256GB, 1 Pack 256GB)
Brand: Povee
Color: 1 Pack 256GB

QAs:

1. Why the capacity is only 59.5GB shows in the computer?

Answer: because of the different algorithms, Mathematically 1GB = 1000MB = 1000x1000KB = 1000x1000x1000 bytes, all the manufactor use this way to mark the capacity, that means 64GB = 64,000,000,000 bytes. But in computer algorithm, 64,000,000,000 bytes = 64000000000 / 1024 /1024 /1024 =59.6GB, so most of the 64GB micro sd cards will be real 59.5GB showed in the computer, and different nand flash from different manafactor will also cause differences in capacity, usually it will be 58-60GB real capacity shows in the computer.

2. Why it doesn't work for my device?

Answer: The default format of the microSD card with capacity 64GB/128GB/256GB are newest exFAT, some early devices are not very compatible with exFAT format, you can format it to FAT32 in the computer and then try again in your device.