I purchased 2 128GB SD cards, one for my Nokia Lumia 1520, and another for my Surface Pro 2, both devices took the card without any issues.As for read/Write speeds, I am sure there are better options, but this is the only 128GB Micro SD card available right now, and Sandisk did an amazing job with the product.And currently at $119.99(For how long, I am not sure), it's a great deal, considering a lot of the good SD cards are in the $140 range still.No issues with either card unmounting itself, put them in, transfer files, and you're good.