BURSTAmong the changes mentioned in yesterday's Nintendo Switch 2 presentation was a note that the new console doesn't just support MicroSD Express cards for augmenting the device's 256GB of internal storage, but it requires MicroSD Express. Whatever plentiful, cheap microSD card you're using in your current Switch, including Sandisk's Nintendo-branded ones, can't migrate over to your Switch 2 alongside all your Switch 1 games.
MicroSD Express, explained
Why is regular-old MicroSD no longer good enough? It all comes down to speed.
Most run-of-the-mill SD and microSD cards you can buy today are using some version of the Ultra High Speed (UHS) standard. Designed to augment the default speed (12.5MB/s) and high speed (25MB/s) from the earliest versions of the SD card standard, the three UHS versions enable data transfers of up to 624MB/s.