As we’ve just explained above, UHS 1 means that a card can reach a lower maximum speed than a UHS 3 card. However, this is far from the only metric that you need to think about while buying an SD card. If speed was the only thing to keep in mind, choosing the best microSD card for 4K video would be easy. However, apart from thinking about how fast your card needs to be — you also need to think about its reliability and quality of manufacturing.